UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

ITEM 1.                  REPORT TO STOCKHOLDERS.

The Annual Report to Stockholders is filed herewith.

Annual Report

Western Asset Municipal Defined Opportunity Trust Inc.
(MTT)

Fund objectives

The Fund’s primary investment objective is to provide high current income exempt from federal income tax* and then to liquidate on or about April 30, 2021 and distribute all of the Fund’s net assets to shareholders. As a secondary investment objective, the Fund will seek total return. There can be no assurance the Fund’s investment objectives will be achieved.

*    Certain investors may be subject to the federal alternative minimum tax (“AMT”), and state and local taxes will apply. Capital gains, if any, are fully taxable. Please consult your personal tax or legal adviser.

What’s inside

Dear Shareholder,

We are pleased to provide the annual report of Western Asset Municipal Defined Opportunity Trust Inc. for the twelve-month reporting period ended November 30, 2010. Please read on for a detailed look at prevailing economic and market conditions during the Fund’s reporting period and to learn how those conditions have affected Fund performance.

As always, we remain committed to providing you with excellent service and a full spectrum of investment choices. We also remain committed to supplementing the support you receive from your financial advisor. One way we accomplish this is through our website, www.leggmason.com/cef. Here you can gain immediate access to market and investment information, including:

·    Fund prices and performance,

·    Market insights and commentaries from our portfolio managers, and

·    A host of educational resources.

We look forward to helping you meet your financial goals.

Sincerely,

R. Jay Gerken, CFA

Chairman, President and Chief Executive Officer

December 31, 2010

Investment commentary

Economic review

While the U.S. economy continued to expand over the twelve months ended November 30, 2010, economic data was mixed and unemployment remained elevated. The Federal Reserve Board (“Fed”)i expressed concerns regarding the direction of the economy and took additional actions in an attempt to spur growth. This initially caused investor sentiment to improve, but the financial markets declined toward the end of the reporting period given a re-escalation of the European sovereign debt crisis.

In September 2010, the National Bureau of Economic Research (“NBER”), the organization charged with determining when recessions start and end, announced that the recession that began in December 2007 had concluded in June 2009. However, the NBER said, “In determining that a trough occurred in June 2009, the committee did not conclude that economic conditions since that month have been favorable or that the economy has returned to operating at normal capacity.” The NBER’s point is well-taken given continued areas of weakness in the U.S. economy.

Although the U.S. Department of Commerce continued to report positive U.S. gross domestic product (“GDP”)ii growth, the expansion has moderated since peaking at 5.0% in the fourth quarter of 2009. A slower drawdown in business inventories and renewed consumer spending were contributing factors spurring the economy’s solid growth at the end of 2009. However, the economy has grown at a more modest pace thus far in 2010. According to the Commerce Department, GDP growth was 3.7% and 1.7% during the first and second quarters of 2010, respectively. GDP growth then edged somewhat higher to 2.6% in the third quarter.

Turning to the job market, after experiencing sharp job losses in 2009, the U.S. Department of Labor reported that over one million new positions were added during the first five months of 2010. Included in that number, however, were 700,000 temporary government jobs tied to the 2010 Census. From June through September, more than 525,000 of these temporary positions were eliminated. This more than offset private sector growth and resulted in a total net loss of 300,000 jobs from June through September. The employment picture then brightened somewhat in October, as 172,000 new jobs were created. Payrolls then increased a disappointing 39,000 in November and the unemployment rate inched up to end the period at 9.8%. The unemployment rate has now exceeded 9.0% since May 2009.

There was mixed news in the housing market during the period. According to the National Association of Realtors (“NAR”), existing-home sales increased 7.0% and 8.0% in March and April, respectively, after sales had fallen for the period from December 2009 through February 2010. The rebound was largely attributed to people rushing to take advantage of the government’s $8,000 tax credit for first-time home buyers that expired at the end of April. However, with the end of the tax credit, existing-home sales then declined from May through July. Sales then rose 7.3% and 10.0% in August and September, respectively. Sales then dipped 2.2% in October and rose 5.6% in November. Looking at home prices, the NAR reported that the median existing-home price for all housing types was $170,600 in November 2010, which was 0.4% higher

Investment commentary (cont’d)

than in November 2009. Prices appeared to stabilize somewhat as the number of existing homes on the market declined in November. The inventory of unsold homes was a 9.5 month supply in November at the current sales level, versus a 10.5 month supply in October.

One overall bright spot for the economy has been the manufacturing sector. Based on the Institute for Supply Management’s PMIiii, the manufacturing sector has grown sixteen consecutive months since it began expanding in August 2009. After reaching a six-year peak of 60.4 in April 2010, PMI data indicated somewhat more modest growth from May through July (a reading below 50 indicates a contraction, whereas a reading above 50 indicates an expansion). The manufacturing sector then expanded at a faster pace in August, before moderating somewhat in September. Manufacturing then grew in October at its fastest pace since May with a reading of 56.9 for the month, before dipping to 56.6 in November.

Financial market overview

During the majority of the reporting period, the financial markets were largely characterized by healthy investor risk appetite and solid results by lower-quality bonds. However, the market experienced a sharp sell-off in late April and in May, during which risk aversion returned and investors flocked to the relative safety of U.S. Treasury securities. Demand for riskier assets then resumed in June and July, followed by another “flight to quality” in August. Risk appetite then returned in September and October before the financial markets again weakened beginning in mid-November.

Due to signs that economic growth was slowing toward the end of the reporting period, the Fed took further actions to spur the economy. At its August 10th meeting, the Fed announced an ongoing program that calls for using the proceeds from expiring agency debt and agency mortgage-backed securities to purchase longer-dated Treasury securities.

In addition, the Fed remained cautious throughout the reporting period given pockets of weakness in the economy. At its meeting in September 2010, the Fed said, “The Committee will continue to monitor the economic outlook and financial developments and is prepared to provide additional accommodation if needed to support the economic recovery. . . .” This led to speculation that the Fed may again move to purchase large amounts of agency and Treasury securities in an attempt to avoid a double-dip recession and ward off deflation.

The Fed then took additional action in early November. Citing that “the pace of recovery in output and employment continues to be slow,” the Fed announced another round of quantitative easing to help stimulate the economy, entailing the purchase of $600 billion of long-term U.S. Treasury securities by the end of the second quarter of 2011. This, coupled with the Fed’s previously announced program to use the proceeds of expiring securities to purchase Treasuries, means it could buy a total of $850 billion to $900 billion of Treasury securities by the end of June 2011.

Fixed-income market review

Continuing the trend that began in the second quarter of 2009, nearly every spread sector (non-Treasury) outperformed equal-durationiv Treasuries during most of the first half of the reporting

period. Over that time, investor confidence was high given encouraging economic data, continued low interest rates, benign inflation and rebounding corporate profits. Robust investor appetite was then replaced with heightened risk aversion toward the end of April and during the month of May. This was due to the escalating sovereign debt crisis in Europe, uncertainties regarding new financial reforms in the U.S. and some worse-than-expected economic data. Most spread sectors then produced positive absolute returns in June and July, as investor demand for these securities again increased. There was another bout of risk aversion in August, given fears that the economy may slip back into a recession. However, with the Fed indicating the possibility of another round of quantitative easing, most spread sectors rallied in September and October. The spread sectors then ended the reporting period on a weak note as financial troubles in Ireland resulted in a re-emergence of the European sovereign debt crisis.

Both short- and long-term Treasury yields fluctuated but, overall, moved lower during the twelve months ended November 30, 2010. When the period began, two- and ten-year Treasury yields were 0.67% and 3.21%, respectively. On April 5, 2010, two- and ten-year Treasury yields peaked at 1.18% and 4.01%, respectively. Subsequent to hitting their highs for the period, yields largely declined during much of the remainder of the reporting period. When the period ended on November 30, 2010, two-year Treasury yields were 0.45%, versus a low of 0.33% earlier in the month. Ten-year Treasury yields ended the period at 2.81%, which was higher than their trough of 2.41% that occurred in October. Longer-term yields moved higher toward the end of the period as fears of future inflation increased in light of the Fed’s additional policy accommodation.

The municipal bond market lagged its taxable bond counterpart over the twelve months ended November 30, 2010. Over that period, the Barclays Capital Municipal Bond Indexv and the Barclays Capital U.S. Aggregate Indexvi returned 4.76% and 6.02%, respectively. The majority of the municipal market’s underperformance occurred in November 2010. Concerns that Congress may not extend the popular Build America Bond program, which was scheduled to expire at the end of 2010, led to a sharp increase in issuance of these securities, which was not readily absorbed by investor demand. In addition, there were some high profile issues regarding the financial well-being of some municipal bond issuers.

As always, thank you for your confidence in our stewardship of your assets.

Sincerely,

R. Jay Gerken, CFA

Chairman, President and
Chief Executive Officer

December 31, 2010

All investments are subject to risk including the possible loss of principal. Past performance is no guarantee of future results. All index performance reflects no deduction for fees, expenses or taxes. Please note that an investor cannot invest directly in an index.

Investment commentary (cont’d)

i                The Federal Reserve Board (“Fed”) is responsible for the formulation of policies designed to promote economic growth, full employment, stable prices and a sustainable pattern of international trade and payments.

ii             Gross domestic product (“GDP”) is the market value of all final goods and services produced within a country in a given period of time.

iii          The Institute for Supply Management’s PMI is based on a survey of purchasing executives who buy the raw materials for manufacturing at more than 350 companies. It offers an early reading on the health of the manufacturing sector.

iv           Duration is the measure of the price sensitivity of a fixed-income security to an interest rate change of 100 basis points. Calculation is based on the weighted average of the present values for all cash flows.

v              The Barclays Capital Municipal Bond Index is a market value weighted index of investment grade municipal bonds with maturities of one year or more.

vi           The Barclays Capital U.S. Aggregate Index is a broad-based bond index comprised of government, corporate, mortgage- and asset-backed issues, rated investment grade or higher, and having at least one year to maturity.

Fund overview

Q. What is the Fund’s investment strategy?

A. The Fund’s primary investment objective is to provide high current income exempt from federal income tax and then to liquidate on or about April 30, 2021 and distribute all of the Fund’s net assets to shareholders. As a secondary investment objective, the Fund will seek total return. There can be no assurance the Fund’s investment objectives will be achieved.

As a fundamental policy, the Fund seeks to achieve its primary investment objective by investing, under normal market conditions, at least 80% of its net assets in investment grade municipal securities, the interest on which is exempt from federal income tax. The Fund may invest up to 20% of its net assets in municipal securities rated below investment grade at the time of purchase by at least one nationally recognized statistical rating organization or which, if unrated, are deemed to be of comparable quality. The Fund may also invest up to 20% of its net assets in investments that generate income that is subject to federal income tax and in municipal securities, the interest on which is subject to the federal alternative minimum tax (“AMT”), and as a result, a portion of the Fund’s distributions may be taxable to common shareholders. The Fund may use a variety of derivative instruments as part of its investment strategies or for hedging and/or risk management purposes.

In purchasing securities and other investments for the Fund, we may take full advantage of the entire range of maturities and durationsi offered by municipal securities and may adjust the average maturity or duration of the Fund’s portfolio from time to time, depending on our assessment of the relative yields available on securities of different maturities and durations and our expectations of future changes in interest rates.

As a fundamental policy, the Fund will not leverage its capital structure by issuing senior securities such as preferred shares or debt instruments. However, the Fund may lend portfolio securities, invest in certain instruments, including inverse floating rate securities, participate in the creation of tender option bonds and enter into transactions such as short sales, that have the economic effect of financial leverage (“effective leverage”), provided that the Fund will not make such investments if, upon completion of the investment, the effective leverage of the Fund would be greater than 10% of the Fund’s total assets.

At Western Asset Management Company (“Western Asset”), the Fund’s subadviser, we utilize a fixed-income team approach, with decisions derived from interaction among various investment management sector specialists. The sector teams are comprised of Western Asset’s senior portfolio managers, research analysts and an in-house economist. Under this team approach, management of client fixed-income portfolios will reflect a consensus of interdisciplinary views within the Western Asset organization. The portfolio managers responsible for development of investment strategy, day-to-day portfolio management, oversight and coordination of the Fund are Stephen A. Walsh, Robert E. Amodeo, David T. Fare and Joseph P. Deane.

Q. What were the overall market conditions during the Fund’s reporting period?

A. During the twelve months ended November 30, 2010, the riskier segments of the fixed-income market produced

Fund overview (cont’d)

strong results and outperformed U.S. Treasuries. This was due, in part, to improving economic conditions following the lengthy downturn from mid-2008 through mid-2009. Also supporting the spread sectors (non-U.S. Treasuries) was overall solid demand from investors seeking incremental yields given the low rates available from short-term fixed-income securities.

The spread sectors rallied during most of the reporting period, with notable exceptions being in late April and May 2010, as well as August and November 2010. Starting toward the end of April, there was a “flight to quality,” triggered by concerns regarding the escalating sovereign debt crisis in Europe. In addition, investor sentiment was negatively impacted by uncertainties surrounding financial reform legislation in the U.S. and signs that economic growth was moderating. Collectively, this caused investors to flock to the relative safety of Treasury securities, driving their yields lower and prices higher.

Robust investor risk appetite largely resumed during June and July, and again in September and October. These turnarounds occurred as the situation in Europe appeared to stabilize, the financial reform bill was signed into law and the Federal Reserve Board (“Fed”)ii continued to indicate that it would keep short-term rates low for an extended period. However, investor risk aversion returned in November when fears regarding the European debt crisis re-emerged.

The yields on two- and ten-year Treasuries began the fiscal year at 0.67% and 3.21%, respectively. Treasury yields fluctuated during the twelve-month reporting period given changing perceptions regarding the economy, interest rates, inflation and deflation. Yields moved sharply lower in October 2010 in anticipation of additional quantitative easing by the Fed. Yields then reversed course toward the end of the period as certain economic data were stronger than expected and there were concerns regarding future inflation. During the fiscal year, two-year Treasury yields moved as high as 1.18% and as low as 0.33%, whereas ten-year Treasuries rose as high as 4.01% and as low as 2.41%. On November 30, 2010, yields on two- and ten-year Treasuries were 0.45% and 2.81%, respectively.

Despite a sharp sell-off in November 2010, municipal bonds posted solid returns during the fiscal year as a whole. Although the fundamentals in the municipal market remained challenging, tax-free bond prices rallied during much of the reporting period. This was due, in part, to generally strong demand as investors were drawn to their attractive yields. In addition, new supply in the tax-exempt market was pared due to increased issuance of Build America Bonds (“BABs”). However, the municipal market ended the fiscal year on a weak note when investor demand could not absorb a sharp increase in new issuance of BABs. This spike in new issuance occurred as municipalities feared that the BAB program, which is scheduled to expire at the end of December, would not be extended by Congress. In addition, there were concerns regarding the financial health of some municipal bond issuers. All told, the Barclays Capital Municipal Bond Indexiii returned 4.76% for the twelve months ended November 30, 2010. Over the same period, the overall taxable bond market, as measured by the

Barclays Capital U.S. Aggregate Indexiv, returned 6.02%.

Q. How did we respond to these changing market conditions?

A. A general theme for the Fund throughout the fiscal year was its underweight exposures to State General Obligation bonds (“GOs”) and Local GOs. These securities are typically economically sensitive, in that the issuing municipality repays bondholders from tax revenues. We avoided GOs given declining tax revenues, ongoing budget challenges and the likelihood of further agency rating downgrades. In contrast, we continued to emphasize essential service revenue bonds. Within this area, we increased the Fund’s exposure to Industrial Revenue bonds, as we continued to find them to be attractively valued. We pared the Fund’s exposure to the Power sector in order to pursue more attractive opportunities.

The Fund employed short U.S. Treasury futures during the reporting period to manage duration. This strategy materially detracted from the Fund’s performance and we closed the position in November 2010.

Performance review

For the twelve months ended November 30, 2010, Western Asset Municipal Defined Opportunity Trust Inc. returned 3.57% based on its net asset value (“NAV”)v and 7.41% based on its New York Stock Exchange (“NYSE”) market price per share. The Fund’s unmanaged benchmark, the Barclays Capital Municipal Bond Index, returned 4.76% for the same period. The Lipper General and Insured Municipal Debt (Unleveraged) Closed-End Funds Category Averagevi returned 3.88% over the same time frame. Please note that Lipper performance returns are based on each fund’s NAV.

Certain investors may be subject to the AMT, and state and local taxes will apply. Capital gains, if any, are fully taxable. Please consult your personal tax or legal adviser.

During the twelve-month period, the Fund made distributions to shareholders totaling $1.12 per share. The performance table shows the Fund’s twelve-month total return based on its NAV and market price as of November 30, 2010. Past performance is no guarantee of future results.

Performance Snapshot as of November 30, 2010

All figures represent past performance and are not a guarantee of future results.

*            Total returns are based on changes in NAV or market price, respectively. Total returns assume the reinvestment of all distributions in additional shares in accordance with the Fund’s Dividend Reinvestment Plan.

Q. What were the leading contributors to performance?

A. The largest contributor to the Fund’s relative performance during the reporting period was our overweight to the Health Care sector, as it outperformed the overall benchmark. An overweight to the Industrial Revenue sector was also rewarded. Within this sector, the Fund’s gas prepayvii securities significantly contributed to performance. These securities performed poorly during the majority of 2008 due to the fallout from the credit crisis. As the financial system recovered, gas prepay securities rallied and generated strong results during much of the fiscal year. Elsewhere, issue selection within the Water & Sewer sector was beneficial for the Fund’s performance.

Fund overview (cont’d)

Q. What were the leading detractors from performance?

A. The largest detractor from relative performance for the period was the use of a short Treasury futures position. This derivative position was employed given our expectations for Treasuries to underperform municipal bonds due to a dramatic increase in Treasury issuance. However, Treasuries outperformed the municipal market over the twelve months ended November 30, 2010. In addition, the Treasury futures position served to shorten the Fund’s overall duration, which negatively impacted performance as the longer portions of the municipal yield curveviii generated the best results during the reporting period.

Looking for additional information?

The Fund is traded under the symbol “MTT” and its closing market price is available in most newspapers under the NYSE listings. The daily NAV is available on-line under the symbol “XMTTX” on most financial websites. Barron’s and the Wall Street Journal’s Monday edition both carry closed-end fund tables that provide additional information. In addition, the Fund issues a quarterly press release that can be found on most major financial websites as well as www.leggmason.com/cef.

In a continuing effort to provide information concerning the Fund, shareholders may call 1-888-777-0102 (toll free), Monday through Friday from 8:00 a.m. to 5:30 p.m. Eastern Time, for the Fund’s current NAV, market price and other information.

Thank you for your investment in Western Asset Municipal Defined Opportunity Trust Inc. As always, we appreciate that you have chosen us to manage your assets and we remain focused on achieving the Fund’s investment goals.

Sincerely,

Western Asset Management Company

December 21, 2010

RISKS: The Fund’s investments are subject to credit risk, inflation risk and interest rate risk. As interest rates rise, bond prices fall, reducing the value of the fixed-income securities held by the Fund. The Fund may invest in lower-rated high-yield bonds which are subject to greater credit risk (risk of default) than higher-rated obligations. The Fund may use derivatives, such as options and futures, which can be illiquid, may disproportionately increase losses, and have a potentially large impact on Fund performance. The Fund may invest up to 10% of its assets in securities that have the economic effects of leverage which can increase the risk and volatility of the Fund. Shares of closed-end exchange-traded funds may trade at a discount or premium to their original offering price and often trade at a discount to their NAV.

The mention of sector breakdowns is for informational purposes only and should not be construed as a recommendation to purchase or sell any securities. The information provided regarding such sectors is not a sufficient basis upon which to make an investment decision. Investors seeking financial advice regarding the appropriateness of investing in any securities or investment strategies discussed should consult their financial professional. Portfolio holdings are subject to change at any time and may not be representative of the portfolio managers’ current or future investments. The Fund’s portfolio composition is subject to change at any time.

All investments are subject to risk including the possible loss of principal. Past performance is no guarantee of future results. All index performance reflects no deduction for fees, expenses or taxes. Please note that an investor cannot invest directly in an index.

The information provided is not intended to be a forecast of future events, a guarantee of future results or investment advice. Views expressed may differ from those of the firm as a whole.

i                Duration is the measure of the price sensitivity of a fixed-income security to an interest rate change of 100 basis points. Calculation is based on the weighted average of the present values for all cash flows.

ii             The Federal Reserve Board (“Fed”) is responsible for the formulation of policies designed to promote economic growth, full employment, stable prices and a sustainable pattern of international trade and payments.

iii          The Barclays Capital Municipal Bond Index is a market value weighted index of investment grade municipal bonds with maturities of one year or more.

iv           The Barclays Capital U.S. Aggregate Index is a broad-based bond index comprised of government, corporate, mortgage- and asset-backed issues, rated investment grade or higher, and having at least one year to maturity.

v              Net asset value (“NAV”) is calculated by subtracting total liabilities and outstanding preferred stock (if any) from the closing value of all securities held by the Fund (plus all other assets) and dividing the result (total net assets) by the total number of the common shares outstanding. The NAV fluctuates with changes in the market prices of securities in which the Fund has invested. However, the price at which an investor may buy or sell shares of the Fund is the Fund’s market price as determined by supply of and demand for the Fund’s shares.

vi           Lipper, Inc., a wholly-owned subsidiary of Reuters, provides independent insight on global collective investments. Returns are based on the twelve-month period ended November 30, 2010, including the reinvestment of all distributions, including returns of capital, if any, calculated among the 8 funds in the Fund’s Lipper category.

vii        Gas prepay bonds are issued to enable a municipal utility to contract for a stated amount of natural gas supply over an extended period of time. The utility contracts with a natural gas supplier to purchase gas at a discount to the spot price of gas at the time of delivery. The bonds are issued to fund future purchases of the gas supplier. Bonds are repaid by the utility from gas sales to its customers, though the ratings are primarily driven by the credit strength of the financial firm that guarantees the performance of the gas supplier.

viii     The yield curve is the graphical depiction of the relationship between the yield on bonds of the same credit quality but different maturities.

Fund at a glance† (unaudited)

Investment breakdown (%) as a percent of total investments

†        The bar graph above represents the composition of the Fund’s investments as of November 30, 2010 and November 30, 2009 and does not include derivatives such as futures contracts. The Fund is actively managed. As a result, the composition of the Fund’s investments is subject to change at anytime.

Spread duration (unaudited)

Economic Exposure — November 30, 2010

Spread duration measures the sensitivity to changes in spreads. The spread over Treasuries is the annual risk-premium demanded by investors to hold non-Treasury securities. Spread duration is quantified as the % change in price resulting from a 100 basis points change in spreads. For a security with positive spread duration, an increase in spreads would result in a price decline and a decline in spreads would result in a price increase. This chart highlights the market sector exposure of the Fund’s portfolio and the exposure relative to the selected benchmark as of the end of the reporting period.

Effective duration (unaudited)

Interest Rate Exposure — November 30, 2010

Effective duration measures the sensitivity to changes in Treasury yields. Effective duration is quantified as the % change in price resulting from a 100 basis points change in Treasury yields. For a security with positive effective duration, an increase in Treasury yields would result in a price decline and a decline in Treasury yields would result in a price increase. This chart highlights the interest rate exposure of the Fund’s portfolio relative to the selected benchmark as of the end of the reporting period.

Schedule of investments

November 30, 2010

Western Asset Municipal Defined Opportunity Trust Inc.

See Notes to Financial Statements.

Schedule of investments (cont’d)

November 30, 2010

Western Asset Municipal Defined Opportunity Trust Inc.

See Notes to Financial Statements.

Western Asset Municipal Defined Opportunity Trust Inc.

(a)         Income from this issue is considered a preference item for purposes of calculating the alternative minimum tax (“AMT”).

(b)        Maturity date shown represents the mandatory tender date.

(c)         Variable rate security. Interest rate disclosed is that which is in effect at November 30, 2010.

(d)        Variable rate demand obligations have a demand feature under which the Fund can tender them back to the issuer or liquidity provider on no more than 7 days notice.

(e)         Maturity date shown is the final maturity date. The security may be sold back to the issuer before final maturity.

#            Aggregate cost for federal income tax purposes is $218,296,973.

See Notes to Financial Statements.

Schedule of investments (cont’d)

November 30, 2010

Western Asset Municipal Defined Opportunity Trust Inc.

Abbreviations used in this schedule:

Summary of Investments by Industry*

*            As a percentage of total investments. Please note that Fund holdings are as of November 30, 2010 and are subject to change.

Ratings Table† (unaudited)

†             As a percentage of total investments.

‡             The ratings shown are based on each portfolio security’s rating as determined by S&P, Moody’s or Fitch, each a Nationally Recognized Statistical Ratings Organization (“NRSRO”). These ratings are the opinions of the NRSRO and are not measures of quality or guarantees of performance. Securities may be rated by other NRSROs, and these ratings may be higher or lower. In the event that a security is rated by multiple NRSROs and receives different ratings, the Fund will treat the security as being rated in the highest rating category received from an NRSRO.

See pages 13 through 16 for definitions of ratings.

See Notes to Financial Statements.

Bond ratings

The definitions of the applicable rating symbols are set forth below:

Long-term security ratings (unaudited)

Standard & Poor’s Ratings Service (“Standard & Poor’s”) Long-term Issue Credit Ratings — Ratings from “AA” to “CCC” may be modified by the addition of a plus (+) or minus (-) sign to show relative standings within the major rating categories.

Long-term security ratings (unaudited) (cont’d)

Moody’s Investors Service (“Moody’s”) Long-term Obligation Ratings — Numerical modifiers 1, 2 and 3 may be applied to each generic rating from “Aa” to “Caa,” where 1 is the highest and 3 the lowest ranking within its generic category.

Fitch Ratings Service (“Fitch”) Structured, Project & Public Finance Obligations — Ratings from “AA” to “CCC” may be modified by the addition of a plus (+) or minus (–) sign to show relative standings within the major rating categories.

Short-term security ratings (unaudited)

Standard & Poor’s Municipal Short-Term Notes Ratings

Standard & Poor’s Short-Term Issues Credit Ratings

Moody’s Variable Rate Demand Obligations (VRDO) Ratings

Short-term security ratings (unaudited) (cont’d)

Moody’s Short-Term Municipal Obligations Ratings

Moody’s Short-Term Obligations Ratings

Fitch’s Short-Term Issuer or Obligations Ratings

Statement of assets and liabilities

November 30, 2010

See Notes to Financial Statements.

Statement of operations

For the Year Ended November 30, 2010

See Notes to Financial Statements.

Statements of changes in net assets

†  For the period March 27, 2009 (commencement of operations) to November 30, 2009.

See Notes to Financial Statements.

Financial highlights

For a share of capital stock outstanding throughout each year ended November 30, unless otherwise noted:

See Notes to Financial Statements.

Notes to financial statements

1. Organization and significant accounting policies

Western Asset Municipal Defined Opportunity Trust Inc. (the “Fund”) was incorporated in Maryland on January 15, 2009 and is registered as a non-diversified, closed-end management investment company under the Investment Company Act of 1940, as amended (the “1940 Act”). The Fund’s primary investment objective is to provide high current income exempt from federal income tax and then to liquidate on or about April 30, 2021 and distribute all of the Fund’s net assets to shareholders. As a secondary investment objective, the Fund will seek total return.

The following are significant accounting policies consistently followed by the Fund and are in conformity with U.S. generally accepted accounting principles (“GAAP”). Estimates and assumptions are required to be made regarding assets, liabilities and changes in net assets resulting from operations when financial statements are prepared. Changes in the economic environment, financial markets and any other parameters used in determining these estimates could cause actual results to differ. Subsequent events have been evaluated through the date the financial statements were issued.

(a) Investment valuation. Securities are valued at the mean between the last quoted bid and asked prices provided by an independent pricing service, which are based on transactions in municipal obligations, quotations from municipal bond dealers, market transactions in comparable securities and various other relationships between securities. Futures contracts are valued daily at the settlement price established by the board of trade or exchange on which they are traded. When prices are not readily available, or are determined not to reflect fair value, the Fund values these securities at fair value as determined in accordance with procedures approved by the Fund’s Board of Directors. Short-term obligations with maturities of 60 days or less are valued at amortized cost, which approximates fair value.

The Fund has adopted Financial Accounting Standards Board Codification Topic 820 (“ASC Topic 820”). ASC Topic 820 establishes a single definition of fair value, creates a three-tier hierarchy as a framework for measuring fair value based on inputs used to value the Fund’s investments, and requires additional disclosure about fair value. The hierarchy of inputs is summarized below.

·        Level 1 — quoted prices in active markets for identical investments

·        Level 2 — other significant observable inputs (including quoted prices for similar investments, interest rates, prepayment speeds, credit risk, etc.)

·        Level 3 — significant unobservable inputs (including the Fund’s own assumptions in determining the fair value of investments)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

Notes to financial statements (cont’d)

The Fund uses valuation techniques to measure fair value that are consistent with the market approach and/or income approach, depending on the type of security and the particular circumstance. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable securities. The income approach uses valuation techniques to discount estimated future cash flows to present value.

The following is a summary of the inputs used in valuing the Fund’s assets carried at fair value:

†  See Schedule of Investments for additional detailed categorizations.

(b) Futures contracts. The Fund may use futures contracts to gain exposure to, or hedge against, changes in the value of interest rates. A futures contract represents a commitment for the future purchase or sale of an asset at a specified price on a specified date.

Upon entering into a futures contract, the Fund is required to deposit cash or cash equivalents with a broker in an amount equal to a certain percentage of the contract amount. This is known as the “initial margin” and subsequent payments (“variation margin”) are made or received by the Fund each day, depending on the daily fluctuation in the value of the contract. The daily changes in contract value are recorded as unrealized gains or losses in the Statement of Operations and the Fund recognizes a realized gain or loss when the contract is closed.