N-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-Q

QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS OF

REGISTERED MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number 811-4992

MFS HIGH YIELD MUNICIPAL TRUST

(Exact name of registrant as specified in charter)

500 Boylston Street, Boston, Massachusetts 02116

(Address of principal executive offices) (Zip code)

Susan S. Newton

Massachusetts Financial Services Company

500 Boylston Street

Boston, Massachusetts 02116

(Name and address of agents for service)

Registrant’s telephone number, including area code: (617) 954-5000

Date of fiscal year end: November 30

Date of reporting period: August 31, 2010

ITEM 1. SCHEDULE OF INVESTMENTS.

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10

Issuer	Shares/Par		Value ($)
Municipal Bonds – 157.4%
Airport & Port Revenue – 3.9%
Dallas Fort Worth, TX, International Airport Rev. Improvement, “B”, AGM, 5%, 2025 $ 3,000,000	$	3,083,670
Maryland Economic Development Corp. Rev. (Terminal Project), “B”, 5.75%, 2035 285,000		297,725
Port Authority NY & NJ, Cons Thirty Seventh, AGM, 5.125%, 2030		1,450,000		1,526,676
			$	4,908,071
General Obligations - General Purpose – 0.4%
Luzerne County, PA, AGM, 6.75%, 2023	$	455,000	$	526,317
General Obligations - Improvement – 0.3%
Guam Government, “A”, 6.75%, 2029	$	140,000	$	159,095
Guam Government, “A”, 7%, 2039		160,000		180,581
			$	339,676
General Obligations - Schools – 2.2%
Beverly Hills, CA, Unified School District, Capital Appreciation, (Election of 2008), 0%, 2029	$	2,195,000	$	903,396
Beverly Hills, CA, Unified School District, Capital Appreciation, (Election of 2008), 0%, 2031		275,000		99,118
Beverly Hills, CA, Unified School District, Capital Appreciation, (Election of 2008), 0%, 2032		280,000		94,685
Beverly Hills, CA, Unified School District, Capital Appreciation, (Election of 2008), 0%, 2033		560,000		177,038
Irving, TX, Independent School District, Capital Appreciation, “A”, PSF, 0%, 2016		1,000,000		906,470
Los Angeles, CA, Unified School District, “D”, 5%, 2034		165,000		173,771
San Jacinto, TX, Community College District, 5.125%, 2038		430,000		457,757
			$	2,812,235
Healthcare Revenue - Hospitals – 37.2%
Allegheny County, PA, Hospital Development Authority Rev. (University of Pittsburgh Medical Center), “A”, 5.375%, 2029	$	440,000	$	472,793
Allegheny County, PA, Hospital Development Authority Rev. (West Penn Allegheny Health), “A”, 5%, 2028		435,000		344,685
Allegheny County, PA, Hospital Development Authority Rev. (West Penn Allegheny Health), “A”, 5.375%, 2040		625,000		474,156
Atchison, KS, Hospital Rev. (Atchison Hospital Assn.), “A”, 6.75%, 2030		320,000		320,528
Birmingham, AL, Baptist Medical Center, Special Care Facilities Rev. (Baptist Health Systems, Inc.), “A”, 5%, 2030		500,000		451,620
Brunswick, GA, Hospital Authority Rev. (Glynn-Brunswick Memorial Hospital), 5.625%, 2034		170,000		180,166
California Health Facilities Financing Authority Rev. (St. Joseph Health System), “A”, 5.75%, 2039		185,000		198,200
California Health Facilities Financing Authority Rev. (Sutter Health), “A”, 5%, 2042		500,000		503,970
California Municipal Finance Authority Rev. (Eisenhower Medical Center), “A”, 5.75%, 2040		40,000		40,931
California Statewide Communities Development Authority Rev. (Catholic Healthcare West), “K”, ASSD GTY, 5.5%, 2041		625,000		662,481
California Statewide Communities Development Authority Rev. (Catholic Healthcare West), “L”, ASSD GTY, 5.25%, 2041		870,000		906,897
California Statewide Communities Development Authority Rev. (Children’s Hospital), 5%, 2047		290,000		243,742
California Statewide Communities Development Authority Rev. (St. Joseph Health System), FGIC, 5.75%, 2047		635,000		659,860
Cullman County, AL, Health Care Authority (Cullman Regional Medical Center), “A”, 6.75%, 2029		60,000		63,177
Delaware County, PA, Authority Rev. (Mercy Health Corp.), ETM, 6%, 2016 (c)		965,000		1,011,281
Delaware County, PA, Authority Rev. (Mercy Health Corp.), ETM, 6%, 2026 (c)		500,000		606,400
Erie County, PA, Hospital Authority Rev. (St. Vincent’s Health), “A”, 7%, 2027		410,000		420,201

1

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Healthcare Revenue - Hospitals – continued
Gage County, NE, Hospital Authority No. 1, Health Care Facilities Rev. (Beatrice Community Hospital & Health Care Center), “B”, 6%, 2025	$	70,000	$	71,862
Gage County, NE, Hospital Authority No. 1, Health Care Facilities Rev. (Beatrice Community Hospital & Health Care Center), “B”, 6.5%, 2030		230,000		235,131
Gage County, NE, Hospital Authority No. 1, Health Care Facilities Rev. (Beatrice Community Hospital & Health Care Center), “B”, 6.75%, 2035		195,000		199,300
Garden City, MI, Hospital Finance Authority Rev. (Garden City Hospital), 5%, 2038		500,000		353,270
Genesee County, NY, Industrial Development Agency Civic Facility Rev. (United Memorial Medical Center), 5%, 2027		90,000		80,315
Harris County, TX, Health Facilities Development Corp., Hospital Rev. (Memorial Hermann Healthcare Systems), “B”, 7.25%, 2035		205,000		237,333
Idaho Health Facilities Authority Rev. (IHC Hospitals, Inc.), ETM, 6.65%, 2021 (c)		2,750,000		3,717,863
Illinois Finance Authority Rev. (Children’s Memorial Hospital), “A”, ASSD GTY, 5.25%, 2047		870,000		897,918
Illinois Finance Authority Rev. (Kewanee Hospital), 5.1%, 2031		400,000		332,400
Illinois Finance Authority Rev. (Provena Health), “A”, 7.75%, 2034		485,000		567,663
Illinois Finance Authority Rev. (Silver Cross Hospital & Medical Centers), 6.875%, 2038		485,000		521,685
Indiana Health & Educational Facilities Finance Authority Rev. (Sisters of St. Francis Health Services, Inc.), “E”, AGM, 5.25%, 2041		660,000		685,667
Indiana Health & Educational Facilities Finance Authority, Hospital Rev. (Clarian Health), “A”, 5%, 2039		1,745,000		1,746,605
Indiana Health & Educational Facilities Finance Authority, Hospital Rev. (Community Foundation of Northwest Indiana), 5.5%, 2037		945,000		945,350
Indiana Health & Educational Financing Authority Rev. (Community Foundation of Northwest Indiana ), “A”, 6%, 2034		425,000		439,565
Johnson City, TN, Health & Educational Facilities Board Hospital Rev. (Mountain States Health Alliance), “A”, 5.5%, 2031		1,120,000		1,133,810
Johnson City, TN, Health & Educational Facilities Board Hospital Rev. (Mountain States Health Alliance), “A”, 5.5%, 2036		410,000		414,440
Kentucky Economic Development Finance Authority, Hospital Facilities Rev. (Baptist Healthcare System), “A”, 5.375%, 2024		300,000		335,076
Kentucky Economic Development Finance Authority, Hospital Facilities Rev. (Baptist Healthcare System), “A”, 5.625%, 2027		100,000		111,168
Kentucky Economic Development Finance Authority, Hospital Facilities Rev. (Owensboro Medical Health System), “A”, 6.375%, 2040		570,000		612,516
Lake County, OH, Hospital Facilities Rev. (Lake Hospital Systems, Inc.), 5.625%, 2029		435,000		439,006
Lebanon County, PA, Health Facilities Authority Rev. (Good Samaritan Hospital), 5.9%, 2028		210,000		205,850
Louisiana Public Facilities Authority Hospital Rev. (Lake Charles Memorial Hospital), 6.375%, 2034		880,000		843,806
Louisville & Jefferson County, KY, Metro Government Health Facilities Rev. (Jewish Hospital & St. Mary’s Healthcare), 6.125%, 2037		1,315,000		1,412,349
Louisville & Jefferson County, KY, Metropolitan Government Healthcare Systems Rev. (Norton Healthcare, Inc.), 5.25%, 2036		1,265,000		1,285,986
Lufkin, TX, Health Facilities Development Corp. Rev. (Memorial Health System), 5.5%, 2032		60,000		57,521
Lufkin, TX, Health Facilities Development Corp. Rev. (Memorial Health System), 5.5%, 2037		60,000		56,804
Maryland Health & Higher Educational Facilities Authority Rev. (Anne Arundel Health System), “A”, 6.75%, 2039		735,000		861,347
Maryland Health & Higher Educational Facilities Authority Rev. (Washington County Hospital), 6%, 2043		120,000		124,006
Massachusetts Health & Educational Facilities Authority Rev. (Boston Medical Center), 5.25%, 2038		1,000,000		961,750

2

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Healthcare Revenue - Hospitals – continued
Massachusetts Health & Educational Facilities Authority Rev. (Jordan Hospital), “E”, 6.75%, 2033	$	250,000	$	251,355
Massachusetts Health & Educational Facilities Authority Rev. (Milford-Whitinsville Hospital), “C”, 5.25%, 2018		500,000		488,300
Massachusetts Health & Educational Facilities Authority Rev. (Quincy Medical Center), “A”, 6.5%, 2038		485,000		444,600
Montgomery, AL, Medical Clinic Board Health Care Facility Rev. (Jackson Hospital & Clinic), 5.25%, 2031		125,000		121,786
Montgomery, AL, Medical Clinic Board Health Care Facility Rev. (Jackson Hospital & Clinic), 5.25%, 2036		825,000		794,714
New Hampshire Business Finance Authority Rev. (Elliot Hospital Obligated Group), “A”, 6%, 2027		585,000		613,747
New Hampshire Health & Education Facilities Authority Rev. (Catholic Medical Center), “A”, 6.125%, 2012 (c)		175,000		194,553
New Hampshire Health & Education Facilities Authority Rev. (Catholic Medical Center), “A”, 6.125%, 2032		25,000		25,471
New Hampshire Health & Educational Facilities Authority Rev. (Memorial Hospital at Conway), 5.25%, 2021		530,000		537,033
New Hanover County, NC, Hospital Rev., AGM, 5.125%, 2031		895,000		949,291
New Jersey Health Care Facilities, Financing Authority Rev. (Robert Wood Johnson University Hospital), 5%, 2031		30,000		30,854
New Jersey Health Care Facilities, Financing Authority Rev. (St. Peter’s University Hospital), 5.75%, 2037		545,000		554,216
New Mexico Hospital Equipment Loan Council, Hospital Rev. (Rehoboth McKinley Christian Hospital), “A”, 5%, 2017		285,000		273,515
New York Dormitory Authority Rev., Non-State Supported Debt (Bronx-Lebanon Hospital Center), LOC, 6.5%, 2030		190,000		216,748
New York Dormitory Authority Rev., Non-State Supported Debt (Bronx-Lebanon Hospital Center), LOC, 6.25%, 2035		115,000		128,928
Norman, OK, Regional Hospital Authority Rev., 5%, 2027		155,000		136,220
Norman, OK, Regional Hospital Authority Rev., 5.375%, 2029		90,000		80,945
Norman, OK, Regional Hospital Authority Rev., 5.375%, 2036		235,000		200,218
Norman, OK, Regional Hospital Authority Rev., 5.125%, 2037		415,000		339,217
Olympia, WA, Healthcare Facilities Authority Rev. (Catholic Health Initiatives), “D”, 6.375%, 2036		1,095,000		1,239,047
Orange County, FL, Health Facilities Authority Hospital Rev. (Orlando Regional Healthcare), 5.75%, 2012 (c)		150,000		167,769
Palomar Pomerado Health Care District, CA, COP, 6.75%, 2039		1,010,000		1,113,565
Philadelphia, PA, Hospitals & Higher Education Facilities Authority Rev. (Temple University Health System), “A”, 6.625%, 2023		375,000		375,218
Philadelphia, PA, Hospitals & Higher Education Facilities Authority Rev. (Temple University Health System), “A”, 5.5%, 2030		480,000		447,086
Rhode Island Health & Educational Building Corp. Rev., Hospital Financing (Lifespan Obligated Group), “A”, ASSD GTY, 7%, 2039		660,000		764,762
Royal Oak, MI, Hospital Finance Authority Rev. (William Beaumont Hospital), 8.25%, 2039		485,000		588,902
Salida, CO, Hospital District Rev., 5.25%, 2036		734,000		621,045
Scottsdale, AZ, Industrial Development Authority Hospital Rev. (Scottsdale Healthcare), “C”, ASSD GTY, 5%, 2035		60,000		61,615
Skagit County, WA, Public Hospital District No. 001 Rev. (Skagit Valley Hospital), 5.75%, 2032		90,000		91,053
South Lake County, FL, Hospital District Rev. (South Lake Hospital), 6.375%, 2034		250,000		256,315
South Lake County, FL, Hospital District Rev. (South Lake Hospital), “A”, 6%, 2029		85,000		89,234
South Lake County, FL, Hospital District Rev. (South Lake Hospital), “A”, 6.25%, 2039		125,000		131,161
Southwestern, IL, Development Authority Rev. (Anderson Hospital), 5.375%, 2015		427,000		429,506

3

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Healthcare Revenue - Hospitals – continued
Southwestern, IL, Development Authority Rev. (Anderson Hospital), 5.5%, 2020	$	550,000	$	552,552
Southwestern, IL, Development Authority Rev. (Anderson Hospital), 5.125%, 2026		500,000		478,705
Sullivan County, TN, Health, Educational & Housing Facilities Board Hospital Rev. (Wellmont Health Systems Project), “C”, 5.25%, 2036		1,085,000		1,037,607
Sumner County, TN, Health, Educational & Housing Facilities Board Rev. (Sumner Regional Health Systems, Inc.), “A”, 5.5%, 2046		375,000		322,500
Tyler, TX, Health Facilities Development Corp. (East Texas Medical Center), “A”, 5.25%, 2032		230,000		224,975
Tyler, TX, Health Facilities Development Corp. (East Texas Medical Center), “A”, 5.375%, 2037		190,000		186,132
Virginia Small Business Financing Authority, Hospital Rev. (Wellmont Health Project), ‘‘A’’, 5.25%, 2037		470,000		454,857
Washington Health Care Facilities Authority Rev. (Multicare Health Systems), “B”, ASSD GTY, 6%, 2039		440,000		484,427
West Contra Costa, CA, Healthcare District, AMBAC, 5.5%, 2029		105,000		110,570
Wisconsin Health & Educational Facilities Authority Rev. (Aurora Health Care, Inc.), 6.4%, 2033		350,000		361,942
Wisconsin Health & Educational Facilities Authority Rev. (Fort Healthcare, Inc.), 6.1%, 2034		750,000		767,415
Wisconsin Health & Educational Facilities Authority Rev. (Wheaton Franciscan Services), 5.75%, 2012 (c)		450,000		489,384
Wisconsin Health & Educational Facilities Authority Rev. (Wheaton Franciscan Services), 5.25%, 2034		935,000		883,865
Wisconsin Health & Educational Facilities Authority Rev. (Wheaton Franciscan Services), “A”, 5.25%, 2025		390,000		391,041
			$	46,952,411
Healthcare Revenue - Long Term Care – 25.5%
ABAG Finance Authority for Non-Profit Corps., CA, Rev. (Casa de las Campanas), 6%, 2037	$	90,000	$	93,005
Abilene, TX, Health Facilities Development Corp., Retirement Facilities Rev. (Sears Methodist Retirement Systems, Inc.), “A”, 5.9%, 2025		750,000		648,255
Abilene, TX, Health Facilities Development Corp., Retirement Facilities Rev. (Sears Methodist Retirement Systems, Inc.), “A”, 7%, 2033		200,000		182,732
Boston, MA, Industrial Development Financing Authority Rev. (Springhouse, Inc.), 5.875%, 2020		235,000		234,988
Bucks County, PA, Industrial Development Authority Retirement Community Rev. (Ann’s Choice, Inc.), “A”, 6.125%, 2025		500,000		501,960
Bucks County, PA, Industrial Development Authority Rev. (Lutheran Community Telford Center), 5.75%, 2027		90,000		80,757
Bucks County, PA, Industrial Development Authority Rev. (Lutheran Community Telford Center), 5.75%, 2037		120,000		101,054
California Statewide Communities Development Authority Rev. (American Baptist Homes of the West), 6.25%, 2039		215,000		219,311
California Statewide Communities Development Authority Rev. (Eskaton Properties, Inc.), 8.25%, 2010 (c)		695,000		719,290
Capital Projects Finance Authority, FL (Glenridge on Palmer Ranch), “A”, 8%, 2012 (c)		500,000		574,585
Chartiers Valley, PA, Industrial & Commercial Development Authority (Friendship Village), “A”, 5.75%, 2020		1,000,000		1,000,340
Chartiers Valley, PA, Industrial & Commercial Development Authority Rev. (Asbury Health Center), 6.375%, 2024		1,000,000		1,003,370
Colorado Health Facilities Authority Rev. (American Housing Foundation, Inc.), 8.5%, 2011 (c)		530,000		578,956
Colorado Health Facilities Authority Rev. (Christian Living Communities Project), “A”, 5.75%, 2037		500,000		451,805

4

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Healthcare Revenue - Long Term Care – continued
Colorado Health Facilities Authority Rev. (Covenant Retirement Communities, Inc.), 5%, 2035	$	1,100,000	$	962,819
Colorado Health Facilities Authority Rev. (Evangelical Lutheran), “A”, 6.125%, 2038		120,000		122,942
Columbus, GA, Housing Authority Rev. (Calvary Community, Inc.), 7%, 2019		400,000		370,072
Cumberland County, PA, Municipal Authority Rev. (Diakon Lutheran Social Ministries), 6.125%, 2029		695,000		727,901
Fulton County, GA, Residential Care Facilities (Canterbury Court), “A”, 6.125%, 2026		500,000		483,760
Hamden, CT, Facility Rev. (Whitney Center Project), “A”, 7.625%, 2030		65,000		70,201
Hamden, CT, Facility Rev. (Whitney Center Project), “A”, 7.75%, 2043		325,000		346,466
Hawaii Department of Budget & Finance, Special Purpose Rev. (15 Craigside Project), “A”, 9%, 2044		140,000		162,033
Houston, TX, Health Facilities Development Corp. (Buckingham Senior Living Community), “A”, 7%, 2014 (c)		500,000		607,460
Howard County, MD, Retirement Facilities Rev. (Vantage House Corp.), “A”, 5.25%, 2033		200,000		159,798
Huntington, NY, Housing Authority Rev. (Gurwin Senior Jewish Residences), “A”, 5.875%, 2019		390,000		384,127
Huntington, NY, Housing Authority Rev. (Gurwin Senior Jewish Residences), “A”, 6%, 2029		650,000		595,413
Illinois Finance Authority Rev. (Evangelical Retirement Homes of Greater Chicago, Inc.), 7.25%, 2045		850,000		886,525
Illinois Finance Authority Rev. (Smith Village), “A”, 6.25%, 2035		1,000,000		879,640
Illinois Health Facilities Authority Rev. (Smith Crossing), “A”, 7%, 2032		525,000		498,372
Indiana Health Facilities Financing Authority Rev. (Hoosier Care, Inc.), “A”, 7.125%, 2034		995,000		916,703
Iowa Finance Authority, Health Care Facilities Rev. (Care Initiatives), 9.25%, 2011 (c)		860,000		938,578
Iowa Finance Authority, Health Care Facilities Rev. (Care Initiatives), “B”, 5.75%, 2018		460,000		435,270
Iowa Finance Authority, Health Care Facilities Rev. (Care Initiatives), “B”, 5.75%, 2028		1,475,000		1,248,868
James City County, VA, Economic Development (WindsorMeade Project), “A”, 5.5%, 2037		440,000		283,404
Kentucky Economic Development Finance Authority Health Facilities Rev. (AHF/Kentucky-Iowa, Inc.), 8%, 2029		375,000		377,993
La Verne, CA, COP (Brethren Hillcrest Homes), “B”, 6.625%, 2025		525,000		531,510
Massachusetts Development Finance Agency Rev. (Adventcare), “A”, 6.75%, 2037		695,000		622,386
Massachusetts Development Finance Agency Rev. (Alliance Health of Brockton, Inc.), “A”, 7.1%, 2032		1,040,000		961,012
Massachusetts Development Finance Agency Rev. (Linden Ponds, Inc.), “A”, 5.5%, 2027		185,000		140,326
Massachusetts Development Finance Agency Rev. (Linden Ponds, Inc.), “A”, 5.75%, 2035		45,000		32,949
Massachusetts Development Finance Agency Rev. (Loomis Communities, Inc.), “A”, 5.625%, 2015		190,000		190,065
Massachusetts Development Finance Agency Rev. (Loomis Communities, Inc.), “A”, 6.9%, 2032		125,000		126,424
Massachusetts Development Finance Agency Rev. (The Groves in Lincoln), “A”, 7.75%, 2039		80,000		85,534
Massachusetts Development Finance Agency Rev. (The Groves in Lincoln), “A”, 7.875%, 2044		115,000		122,718
Massachusetts Industrial Finance Agency Rev. (GF/Massachusetts, Inc.), 8.3%, 2023		725,000		370,446
Metropolitan Government of Nashville & Davidson County, TN, Health & Educational Facilities Board Rev. (Blakeford at Green Hills), 5.65%, 2024		575,000		540,782
Montgomery County, PA, Industrial Development Authority Rev. (Whitemarsh Continuing Care), 6.125%, 2028		150,000		131,436
Montgomery County, PA, Industrial Development Authority Rev. (Whitemarsh Continuing Care), 6.25%, 2035		600,000		507,714

5

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Healthcare Revenue - Long Term Care – continued
New Jersey Economic Development Authority Rev. (Lions Gate), “A”, 5.75%, 2025	$	400,000	$	370,156
New Jersey Economic Development Authority Rev. (Lions Gate), “A”, 5.875%, 2037		300,000		261,567
New Jersey Economic Development Authority Rev. (Seabrook Village, Inc.), 5.25%, 2026		500,000		462,905
New Jersey Economic Development Authority Rev. (Seabrook Village, Inc.), 5.25%, 2036		500,000		442,930
New Jersey Economic Development Authority Rev. (Seabrook Village, Inc.), “A”, 8.25%, 2010 (c)		700,000		718,109
Norfolk, VA, Redevelopment & Housing Authority Rev. (Fort Norfolk Retirement Community), “A”, 6.125%, 2035		195,000		179,642
Roseville, MN, Elder Care Facilities (Care Institute, Inc.), 7.75%, 2023		1,630,000		1,280,805
Savannah, GA, Economic Development Authority, First Mortgage (Marshes of Skidway), “A”, 7.4%, 2034		350,000		349,178
Shelby County, TN, Health, Educational & Housing Facilities Board Rev. (Germantown Village), “A”, 7.25%, 2034		300,000		300,723
South Carolina Jobs & Economic Development Authority Rev. (Woodlands at Furman), “A”, 6%, 2027		280,000		223,695
South Carolina Jobs & Economic Development Authority Rev. (Woodlands at Furman), “A”, 6%, 2042		260,000		188,950
South Carolina Jobs & Economic Development Authority, Health Facilities Rev. (Wesley Commons), 5.3%, 2036		200,000		162,960
St. John’s County, FL, Industrial Development Authority Rev. (Glenmoor Project), “A”, 5.25%, 2026		500,000		419,320
St. John’s County, FL, Industrial Development Authority Rev. (Presbyterian Retirement), “A”, 6%, 2045		610,000		630,203
Tarrant County, TX, Cultural Education Facilities Finance Corp. Retirement Facility (Air Force Village), 6.125%, 2029		550,000		563,728
Tarrant County, TX, Cultural Education Facilities Finance Corp. Retirement Facility (Air Force Village), 6.375%, 2044		415,000		422,897
Tarrant County, TX, Cultural Education Facilities Finance Corp. Retirement Facility (Stayton at Museum Way), 8.25%, 2044		770,000		783,721
Travis County, TX, Health Facilities Development Corp. Rev. (Westminster Manor Health), 7%, 2030		130,000		135,352
Travis County, TX, Health Facilities Development Corp. Rev. (Westminster Manor Health), 7.125%, 2040		195,000		203,011
Westmoreland County, PA, Industrial Development Authority Rev. (Redstone Retirement Community), “A”, 5.875%, 2032		600,000		516,264
Westmoreland County, PA, Industrial Development Retirement Authority Rev. (Redstone Retirement Community), “A”, 5.75%, 2026		1,250,000		1,119,538
Wisconsin Health & Educational Facilities Authority Rev. (All Saints Assisted Living Project), 6%, 2037		180,000		165,598
			$	32,113,307
Healthcare Revenue - Other – 0.6%
Massachusetts Health & Educational Facilities Authority Rev. (Civic Investments, Inc.), “A”, 9%, 2012 (c)	$	650,000	$	747,221
Industrial Revenue - Airlines – 5.3%
Alliance Airport Authority, Inc., TX (American Airlines, Inc.), 5.25%, 2029	$	1,560,000	$	1,154,322
Chicago, IL, O’Hare International Airport Special Facilities Rev. (American Airlines, Inc.), 5.5%, 2030		1,025,000		820,328
Clayton County, GA, Development Authority Special Facilities Rev. (Delta Airlines, Inc.), “A”, 8.75%, 2029		200,000		224,992
Clayton County, GA, Development Authority Special Facilities Rev. (Delta Airlines, Inc.), “B”, 9%, 2035		150,000		161,657
Dallas Fort Worth, TX, International Airport Facility Improvement Corp. (American Airlines, Inc.), 5.5%, 2030		750,000		577,920

6

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Industrial Revenue - Airlines – continued
Houston, TX, Airport Systems Rev., Special Facilities (Continental Airlines, Inc.), “E”, 7%, 2029	$	200,000	$	200,990
New Jersey Economic Development Authority, Special Facilities Rev. (Continental Airlines, Inc.), 6.25%, 2029		535,000		515,975
New Jersey Economic Development Authority, Special Facilities Rev. (Continental Airlines, Inc.), 9%, 2033		1,250,000		1,317,288
New York, NY, City Industrial Development Agencies Rev. (American Airlines, Inc.), 7.5%, 2016		600,000		619,818
New York, NY, City Industrial Development Agencies Rev. (American Airlines, Inc.), 7.75%, 2031		385,000		405,120
New York, NY, City Industrial Development Agencies Rev. (American Airlines, Inc.), FRN, 7.625%, 2025		155,000		161,862
New York, NY, City Industrial Development Agency Special Facility Rev. (American Airlines, Inc.), “B”, 8.5%, 2028		500,000		514,560
			$	6,674,832
Industrial Revenue - Chemicals – 1.4%
Brazos River, TX, Harbor Navigation District (Dow Chemical Co.), “B-2”, 4.95%, 2033	$	400,000	$	395,988
Michigan Strategic Fund Ltd. Obligation Rev. (Dow Chemical Co.), 6.25%, 2014		655,000		741,997
Port of Bay, TX, City Authority (Hoechst Celanese Corp.), 6.5%, 2026		660,000		662,323
			$	1,800,308
Industrial Revenue - Environmental Services – 1.3%
California Pollution Control Financing Authority, Solid Waste Disposal Rev. (Republic Services, Inc.), “B”, 5.25%, 2023 (b)	$	135,000	$	143,420
California Pollution Control Financing Authority, Solid Waste Disposal Rev. (Waste Management, Inc.), “C”, 5.125%, 2023		655,000		663,764
Carbon County, UT, Solid Waste Disposal Rev. (Laidlaw Environmental), “A”, 7.45%, 2017		500,000		500,655
Gulf Coast Waste Disposal Authority, TX (Waste Management, Inc.), “A”, 5.2%, 2028		360,000		366,574
			$	1,674,413
Industrial Revenue - Metals – 0.3%
State of Indiana Finance Authority, Environmental Rev. (U.S. Steel Corp.), 6%, 2026	$	390,000	$	415,081
Industrial Revenue - Other – 3.7%
Annawan, IL, Tax Increment Rev. (Patriot Renewable Fuels LLC), 5.625%, 2018	$	350,000	$	285,761
California Statewide Communities, Development Authority Facilities (Microgy Holdings Project), 9%, 2038 (d)		53,546		5,205
Gulf Coast, TX, Industrial Development Authority Rev. (CITGO Petroleum Corp.), 8%, 2028		375,000		377,651
Houston, TX, Industrial Development Corp. (United Parcel Service, Inc.), 6%, 2023		435,000		429,737
Indianapolis, IN, Airport Authority Rev., Special Facilities (FedEx Corp.), 5.1%, 2017		500,000		523,180
Michigan Strategic Fund Rev. (Michigan Sugar Co.), “A”, 6.25%, 2015		1,000,000		963,260
New Jersey Economic Development Authority Rev. (GMT Realty LLC), “B”, 6.875%, 2037		1,000,000		846,470
Virgin Islands Government Refinery Facilities Rev. (Hovensa Coker Project), 6.5%, 2021		250,000		257,073
Virgin Islands Public Finance Authority, Refinery Facilities Rev. (Hovensa Coker Project), 5.875%, 2022		400,000		406,332
Will-Kankakee, IL, Regional Development Authority Rev. (Flanders Corp.), 6.5%, 2017		555,000		554,861
			$	4,649,530
Industrial Revenue - Paper – 3.5%
Beauregard Parish, LA (Boise Cascade Corp.), 6.8%, 2027	$	1,000,000	$	1,005,330
Bedford County, VA, Industrial Development Authority Rev. (Nekooska Packaging Corp.), 5.6%, 2025		400,000		381,816

7

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Industrial Revenue - Paper – continued
Brunswick & Glynn County, GA, Development Authority Rev. (Georgia-Pacific LLC), 5.55%, 2026	$	465,000	$	436,937
Courtland, AL, Industrial Development Board Solid Waste Disposal Rev. (Champion International Corp.), 6%, 2029		1,000,000		1,002,480
Escambia County, FL, Environmental Improvement Rev. (International Paper Co.), “A”, 5%, 2026		980,000		977,824
Escambia County, FL, Environmental Improvement Rev. (International Paper Co.), “A”, 4.75%, 2030		290,000		267,943
Phenix City, AL, Industrial Development Board Environmental Improvement Rev., “A” (Mead Westvaco Coated Board Project), 6.35%, 2035		400,000		400,460
			$	4,472,790
Miscellaneous Revenue - Entertainment & Tourism – 1.7%
Agua Caliente Band of Cahuilla Indians, CA, Rev., 5.6%, 2013 (n)	$	495,000	$	516,622
Brooklyn, NY, Arena Local Development Corp. (Barclays Center Project), 6%, 2030		135,000		144,565
Brooklyn, NY, Arena Local Development Corp. (Barclays Center Project), 6.25%, 2040		85,000		90,647
Brooklyn, NY, Arena Local Development Corp. (Barclays Center Project), 6.375%, 2043		65,000		69,650
Cow Creek Band of Umpqua Tribe of Indians, OR, “C”, 5.625%, 2026 (n)		650,000		526,266
Mashantucket Western Pequot Tribe, CT, “B”, 0%, 2018 (a)(n)		1,100,000		399,509
New York Liberty Development Corp. Rev. (National Sports Museum), “A”, 6.125%, 2019 (d)		351,999		1,056
New York, NY, City Industrial Development Agency Rev. (Queens Baseball Stadium), ASSD GTY, 6.125%, 2029		30,000		34,407
New York, NY, City Industrial Development Agency Rev. (Queens Baseball Stadium), ASSD GTY, 6.375%, 2039		25,000		28,168
New York, NY, City Industrial Development Agency Rev. (Queens Baseball Stadium), ASSD GTY, 6.5%, 2046		100,000		113,532
Seminole Tribe, FL, Special Obligation Rev., “A”, 5.25%, 2027 (n)		280,000		259,431
			$	2,183,853
Miscellaneous Revenue - Other – 2.7%
Austin, TX, Convention Center (Convention Enterprises, Inc.), “A”, SYNCORA, 5.25%, 2024	$	305,000	$	287,658
Capital Trust Agency, FL (Aero Syracuse LLC), 6.75%, 2032		350,000		343,371
Dallas, TX, Civic Center Convention Complex Rev., ASSD GTY, 5.25%, 2034		845,000		900,863
New York Liberty Development Corp., Liberty Rev. (One Bryant Park LLC), 6.375%, 2049		955,000		1,019,052
Summit County, OH, Port Authority Building Rev. (Twinsburg Township), “D”, 5.125%, 2025		630,000		559,100
V Lakes Utility District, MS, Water Systems Rev., 7%, 2037		300,000		278,826
			$	3,388,870
Multi-Family Housing Revenue – 6.2%
Broward County, FL, Housing Finance Authority Rev. (Chaves Lakes Apartments Ltd.), “A”, 7.5%, 2040	$	500,000	$	500,090
Capital Trust Agency, FL, Housing Rev. (Atlantic Housing Foundation), “B”, 7%, 2032		625,000		267,606
Charter Mac Equity Issuer Trust, FHLMC, 6%, 2019 (n)		1,000,000		1,029,900
Charter Mac Equity Issuer Trust, “B”, FHLMC, 7.6%, 2010 (b)(n)		500,000		508,415
Clay County, FL, Housing Finance Authority Rev. (Madison Commons Apartments), “A”, 7.45%, 2040		492,770		483,447
District of Columbia Housing Finance Agency (Henson Ridge), “E”, FHA, 5.1%, 2037		655,000		658,661
Durham, NC, Durham Housing Authority Rev. (Magnolia Pointe Apartments), 5.65%, 2038 (b)		925,760		746,625
El Paso County, TX, Housing Finance Corp. (American Housing Foundation), “C”, 8%, 2032		280,000		280,879

8

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Multi-Family Housing Revenue – continued
El Paso County, TX, Housing Finance Corp. (American Housing Foundation), “D”, 10%, 2032	$	285,000	$	285,752
Minneapolis, MN, Student Housing Rev. (Riverton Community Housing Project), “A”, 5.7%, 2040		500,000		406,285
Mississippi Home Corp., Rev. (Kirkwood Apartments), 3.4%, 2037		605,000		386,480
MuniMae TE Bond Subsidiary LLC, 5.8%, 2049 (z)		1,000,000		688,740
New Mexico Mortgage Finance Authority, Multi-Family Housing Rev. (Sun Pointe Apartments), “E”, FHA, 4.8%, 2040		500,000		499,210
Resolution Trust Corp., Pass-Through Certificates, “1993”, 8.5%, 2016 (z)		455,481		435,800
Wilmington, DE, Multi-Family Housing Rev. (Electra Arms Senior Associates), 6.25%, 2028		805,000		690,875
			$	7,868,765
Sales & Excise Tax Revenue – 4.6%
Bolingbrook, IL, Sales Tax Rev., 6.25%, 2024	$	500,000	$	319,555
Massachusetts School Building Authority, Dedicated Sales Tax Rev., AMBAC, 4.75%, 2032		840,000		887,796
Metropolitan Pier & Exposition Authority, State Tax Rev., Capital Appreciation, NATL, 0%, 2015		3,000,000		2,595,600
Metropolitan Pier & Exposition Authority, State Tax Rev., Capital Appreciation, ETM, FGIC, 0%, 2014 (c)		1,010,000		966,752
Regional Transportation District, CO, Private Activity Rev. (Denver Transportation Partners), 6%, 2034		630,000		665,482
Regional Transportation District, CO, Private Activity Rev. (Denver Transportation Partners), 6%, 2041		300,000		313,605
			$	5,748,790
Single Family Housing - Local – 1.3%
Minneapolis & St. Paul Housing Authority Rev. (City Living), “A-2”, GNMA, 5%, 2038	$	571,876	$	574,541
Pittsburgh, PA, Urban Redevelopment Authority Rev., “C”, GNMA, 4.8%, 2028		1,000,000		1,026,690
			$	1,601,231
Single Family Housing - State – 2.6%
California Housing Finance Agency Rev., “G”, 5.5%, 2042	$	415,000	$	411,531
Colorado Housing & Finance Authority, “A”, 5.5%, 2029		1,315,000		1,415,216
Iowa Finance Authority, Single Family Mortgage Rev., “E”, 5.4%, 2032		615,000		636,919
Kentucky Counties Single Family Mortgage Rev., “A”, NATL, 9%, 2016		5,000		4,999
North Dakota Housing Finance Agency Rev., “A”, 4.85%, 2021		280,000		287,515
Virginia Housing Development Authority, Commonwealth Mortgage, “A-5”, 4.4%, 2015		210,000		217,776
Virginia Housing Development Authority, Commonwealth Mortgage, “A-5”, 4.4%, 2015		340,000		350,115
			$	3,324,071
Solid Waste Revenue – 0.1%
Pennsylvania Economic Development Financing Authority, Sewer Sludge Disposal Rev. (Philadelphia Biosolids Facility), 6.25%, 2032	$	75,000	$	81,449
State & Agency - Other – 0.5%
Commonwealth of Puerto Rico (Mepsi Campus), “A”, 6.25%, 2024	$	100,000	$	100,277
Commonwealth of Puerto Rico (Mepsi Campus), “A”, 6.5%, 2037		500,000		480,915
			$	581,192
State & Local Agencies – 4.7%
Dorchester County, SC, School District No. 2, Growth Remedy Opportunity Tax Hike, 5.25%, 2029	$	500,000	$	525,940
Guam Government Department of Education (John F. Kennedy High School), “A”, COP, 6.875%, 2040		295,000		301,590
Laurens County, SC, School District No. 55, Installment Purchase Rev., 5.25%, 2030		700,000		705,362
Michigan Building Authority Rev., Facilities Program, “I”, 5%, 2024 (c)		45,000		47,325
Michigan Building Authority Rev., Facilities Program, “I”, 5%, 2024		955,000		989,265

9

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
State & Local Agencies – continued
New York Metropolitan Transportation Authority, “A”, 5.125%, 2029	$	800,000	$	841,080
Newberry, SC, Investing in Children’s Education (Newberry County School District Program), 5%, 2030		400,000		405,120
Philadelphia, PA, Municipal Authority Rev., 6.5%, 2034		135,000		145,176
Puerto Rico Public Finance Corp., “E”, 6%, 2026		820,000		1,114,388
Puerto Rico Public Finance Corp., “E”, ETM, 6%, 2026 (c)		80,000		107,518
Wisconsin General Fund Annual Appropriation Rev., “A”, 5.75%, 2033		660,000		748,460
			$	5,931,224
Student Loan Revenue – 0.5%
Massachusetts Educational Financing Authority, Education Loan Rev., “H”, ASSD GTY, 6.35%, 2030	$	505,000	$	561,555
Massachusetts Educational Financing Authority, Education Loan Rev., “I-A”, 5.5%, 2022		25,000		27,384
			$	588,939
Tax - Other – 1.2%
Dallas County, TX, Flood Control District, 7.25%, 2032	$	750,000	$	786,053
New York, NY, City Transitional Finance Authority Building Aid Rev., “S-3”, 5.25%, 2039		440,000		479,741
Virgin Islands Public Finance Authority Rev. (Diageo Project), “A”, 6.75%, 2037		205,000		234,288
			$	1,500,082
Tax Assessment – 8.9%
Anne Arundel County, MD, Special Obligation (National Business Park-North Project), 6.1%, 2040	$	140,000	$	141,947
Atlanta, GA, Tax Allocation (Eastside Project), “B”, 5.4%, 2020		500,000		516,235
Ave Maria Stewardship Community District, FL, “A”, 5.125%, 2038		150,000		117,461
Capital Region Community Development District, FL, Capital Improvement Rev., “A”, 7%, 2039		235,000		236,349
Celebration Community Development District, FL, “A”, 6.4%, 2034		690,000		702,958
Channing Park Community Development District, FL, 5.3%, 2038		360,000		284,112
Chicago, IL, Tax Increment Allocation (Pilsen Redevelopment), “B”, 6.75%, 2022		310,000		305,521
Du Page County, IL, Special Service Area No. 31 Special Tax (Monarch Landing Project), 5.625%, 2036		250,000		199,678
Durbin Crossing Community Development District, FL, Special Assessment, “B-1”, 4.875%, 2010		100,000		95,128
Grand Bay at Doral Community Development District, FL, “A”, 6%, 2039		90,000		40,801
Grand Bay at Doral Community Development District, FL, “B”, 6%, 2017		545,000		248,536
Heritage Harbour North Community Development District, FL, Capital Improvement Rev., 6.375%, 2038		315,000		268,090
Homestead, FL, Community Development District, Special Assessment, “A”, 6%, 2037		365,000		226,023
Homestead, FL, Community Development District, Special Assessment, “B”, 5.9%, 2013		170,000		104,169
Huntington Beach, CA, Community Facilities District, Special Tax (Grand Coast Resort), “2000-1”, 6.45%, 2031		500,000		504,720
Lincolnshire, IL, Special Service Area No. 1 (Sedgebrook Project), 6.25%, 2034		250,000		219,700
Magnolia Park Community Development District, FL, Special Assessment, “A”, 6.15%, 2039		615,000		425,592
Main Street Community Development District, FL, “A”, 6.8%, 2038		285,000		248,221
Main Street Community Development District, FL, “B”, 6.9%, 2017		225,000		215,262
Northwest Metropolitan District No. 3, CO, 6.25%, 2035		500,000		400,660
Oakmont Grove Community Development District, FL, “A”, 5.4%, 2038 (d)		300,000		111,000
Ohio County, WV, Commission Tax Increment Rev. (Fort Henry Centre), “A”, 5.85%, 2034		125,000		123,408
Orlando, FL, Special Assessment Rev. (Conroy Road Interchange Project), “A”, 5.8%, 2026		300,000		299,361

10

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Tax Assessment – continued
Plano, IL, Special Service Area No. 4 (Lakewood Springs Project Unit 5-B), 6%, 2035	$	1,472,000	$	1,289,840
San Diego, CA, Redevelopment Agency, Tax Allocation, AGM, 0%, 2018		1,015,000		716,174
Sarasota National Community Development District, FL, Special Assessment Rev., 5.3%, 2039 (d)		800,000		256,000
Sweetwater Creek Community Development District, FL, Capital Improvement Rev., 5.5%, 2038		190,000		85,500
Tolomato Community Development District, FL, Special Assessment, 6.65%, 2040		585,000		433,549
Tuscany Reserve Community Development District, FL, Special Assessment, “B”, 5.25%, 2016		185,000		120,707
Volo Village, IL, Special Service Area No. 3, Special Tax (Symphony Meadows Project), “1”, 6%, 2036		484,000		366,335
West Villages Improvement District, FL, Special Assessment Rev. (Unit of Development No. 3), 5.5%, 2037		480,000		240,038
Westchester, FL, Community Development District No. 1 (Community Infrastructure), 6.125%, 2035		275,000		235,480
Westridge, FL, Community Development District, Capital Improvement Rev., 5.8%, 2037 (d)		960,000		364,800
Wyandotte County-Kansas City, KS, Unified Government Transportation Development District (Legends Village West Project), 4.875%, 2028		580,000		437,152
Yorba Linda, CA, Redevelopment Agency, Tax Allocation Rev., “A”, NATL, 0%, 2024		1,325,000		601,802
			$	11,182,309
Tobacco – 7.1%
Buckeye, OH, Tobacco Settlement Financing Authority, “A-2”, 5.875%, 2030	$	590,000	$	480,006
Buckeye, OH, Tobacco Settlement Financing Authority, “A-2”, 5.875%, 2047		2,810,000		2,039,667
Buckeye, OH, Tobacco Settlement Financing Authority, “A-2”, 6.5%, 2047		785,000		626,155
Golden State, CA, Tobacco Securitization Corp., Tobacco Settlement Rev., “A-1”, 6.25%, 2013 (c)(f)		1,155,000		1,280,895
Golden State, CA, Tobacco Securitization Corp., Tobacco Settlement Rev., Asset Backed, “A-1”, 5%, 2033		440,000		346,804
Inland Empire, CA, Tobacco Securitization Corp., Tobacco Settlement Rev., Asset Backed, Capital Appreciation, “C-1”, 0%, 2036		1,815,000		97,411
Michigan Tobacco Settlement Finance Authority Rev., Asset Backed, “A”, 6%, 2048		1,490,000		1,129,629
New Jersey Tobacco Settlement Financing Corp., “1-A”, 5%, 2041		450,000		307,616
Rhode Island Tobacco Settlement Authority, 6%, 2023		1,530,000		1,547,473
Virginia Tobacco Settlement Financing Corp., “B-1”, 5%, 2047		830,000		556,988
Washington Tobacco Settlement Authority Rev., 6.625%, 2032		500,000		504,350
			$	8,916,994
Toll Roads – 4.1%
E-470 Public Highway Authority, CO, Capital Appreciation, “B”, NATL, 0%, 2018	$	1,500,000	$	998,190
Pennsylvania Turnpike Commission, Capital Appreciation, “C”, AGM, 0% to 2016, 6.25% to 2033		1,440,000		1,182,182
San Joaquin Hills, CA, Transportation Corridor Agency, Toll Road Rev., Capital Appreciation, “A”, NATL, 0%, 2015		3,000,000		2,336,190
Texas Private Activity Bond, Surface Transportation Corp., 7%, 2040		615,000		670,578
			$	5,187,140
Universities - Colleges – 9.4%
Brevard County, FL, Industrial Development Rev. (TUFF Florida Tech LLC Project), 6.75%, 2039	$	540,000	$	572,071
California Educational Facilities Authority Rev. (University of Southern California), “A”, 5.25%, 2038		1,270,000		1,406,335
California Municipal Finance Authority Rev. (Biola University), 5.8%, 2028		100,000		106,744
Florida State University Board of Governors, System Improvement Rev., 6.25%, 2030		1,000,000		1,167,490
Grand Valley, MI, State University Rev., 5.5%, 2027		135,000		147,486
Grand Valley, MI, State University Rev., 5.625%, 2029		65,000		70,894

11

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Universities - Colleges – continued
Harris County, TX, Cultural Education Facilities Rev. (Baylor College of Medicine), “D”, 5.625%, 2032	$	540,000	$	536,900
Illinois Finance Authority Rev. (Illinois Institute of Technology), “A”, 5%, 2036		110,000		99,421
Illinois Finance Authority Rev. (Roosevelt University Project), 6.25%, 2029		670,000		716,357
Illinois Finance Authority Rev. (Roosevelt University Project), 6.5%, 2039		155,000		166,180
Iowa Higher Education Loan Authority Rev., Private College Facilities (Upper Iowa University), 5.75%, 2030		80,000		81,769
Iowa Higher Education Loan Authority Rev., Private College Facilities (Upper Iowa University), 6%, 2039		90,000		92,796
Massachusetts Health & Educational Facilities Authority Rev. (Simmons College), “I”, 8%, 2029		255,000		293,602
Massachusetts Health & Educational Facilities Authority Rev. (Suffolk University), “A”, 6.25%, 2030		725,000		790,062
Massachusetts Health & Educational Facilities Authority Rev. (Suffolk University), “A”, 5.75%, 2039		455,000		478,419
Ohio Higher Education Facilities Rev. (Ashland University Project), 6.25%, 2024		660,000		689,159
Savannah, GA, Economic Development Authority Rev. (AASU Student Union LLC), ASSD GTY, 5.125%, 2039		1,320,000		1,396,679
University of Illinois Rev. (Auxiliary Facilities Systems), “A”, 5.125%, 2029		1,880,000		2,043,616
University of Southern Indiana Rev. (Student Fee), “J”, ASSD GTY, 5.75%, 2028		300,000		343,806
University of Southern Mississippi Educational Building Corp. Rev. (Campus Facilities Project), 5.25%, 2032		220,000		243,228
University of Southern Mississippi, Educational Building Corp. Rev. (Campus Facilities Project), 5.375%, 2036		80,000		88,178
Washington Higher Education Facilities Authority Rev. (Whitworth University), 5.875%, 2034		280,000		300,647
			$	11,831,839
Universities - Dormitories – 0.6%
California Statewide Communities Development Authority Rev. (Lancer Educational Student Housing Project), 5.625%, 2033	$	735,000	$	621,465
Pennsylvania Higher Education Facilities Authority Rev. (Edinboro University Foundation), 5.8%, 2030		80,000		81,900
Pennsylvania Higher Education Facilities Authority Rev. (Edinboro University Foundation), 6%, 2043		110,000		113,029
			$	816,394
Universities - Secondary Schools – 1.7%
California Statewide Communities Development Authority Rev., COP (Crossroads Schools for the Arts & Sciences), 6%, 2028	$	950,000	$	952,955
Clifton, TX, Higher Education Finance Corp. Rev. (Uplift Education), “A”, 6.125%, 2040		215,000		222,162
Clifton, TX, Higher Education Finance Corp. Rev. (Uplift Education), “A”, 6.25%, 2045		135,000		140,581
Colorado Housing Finance Development Rev. (Evergreen Country Day School), 5.875%, 2037		175,000		123,865
La Vernia, TX, Higher Education Finance Corp. Rev. (KIPP, Inc.), “A”, 6.25%, 2039		195,000		206,776
Lee County, FL, Industrial Development Authority Rev. (Lee Charter Foundation), “A”, 5.375%, 2037		535,000		448,410
Philadelphia, PA, Authority for Industrial Development Rev. (MaST Charter School), 6%, 2035		50,000		51,618
			$	2,146,367
Utilities - Cogeneration – 0.6%
Puerto Rico Industrial, Tourist, Educational, Medical & Environmental Central Facilities (Cogeneration Facilities - AES Puerto Rico Project), 6.625%, 2026	$	320,000	$	322,870
Suffolk County, NY, Industrial Development Agency Rev. (Nissequoque Cogeneration Partners Facilities), 5.5%, 2023		550,000		500,313
			$	823,183

12

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Utilities - Investor Owned – 6.3%
Brazos River Authority, TX, Pollution Control Rev. (TXU Electric Co. LLC), “C”, 5.75%, 2036 (b)	$	150,000	$	144,000
Brazos River Authority, TX, Pollution Control Rev. (TXU Electric Co. LLC), “C”, 6.75%, 2038		555,000		276,884
Brazos River Authority, TX, Pollution Control Rev. (TXU Electric Co. LLC), “D”, 5.4%, 2029 (b)		45,000		30,145
Bryant, IL, Pollution Control Rev. (Central Illinois Light Co.), 5.9%, 2023		975,000		978,286
Chula Vista, CA, Industrial Development Rev. (San Diego Gas), 5.875%, 2034		245,000		278,986
Farmington, NM, Pollution Control Rev. (Public Service New Mexico), “D”, 5.9%, 2040		500,000		521,395
Maricopa County, AZ, Pollution Control Corp., Pollution Control Rev. (Arizona Public Service Co.), “D”, 6%, 2029 (b)		475,000		520,410
Massachusetts Development Finance Agency, Solid Waste Disposal Rev. (Dominion Energy Brayton), 5.75%, 2042 (b)		85,000		92,673
Matagorda County, TX, Pollution Control Rev. (Central Power & Light Co.), “A”, 6.3%, 2029		275,000		307,786
Mississippi Business Finance Corp., Pollution Control Rev. (Systems Energy Resources Project), 5.875%, 2022		1,500,000		1,504,425
New Hampshire Business Finance Authority, Pollution Control Rev. (Public Service of New Hampshire), “B”, NATL, 4.75%, 2021		250,000		252,978
Owen County, KY, Waterworks System Rev. (American Water Co. Project), “A”, 6.25%, 2039		205,000		226,006
Pennsylvania Economic Development Financing Authority (Allegheny Energy Supply Co. LLC), 7%, 2039		600,000		679,536
Pima County, AZ, Industrial Development Authority Rev. (Tucson Electric Power Co.), 5.75%, 2029		1,015,000		1,041,217
Sabine River Authority, TX, Pollution Control Rev. (TXU Electric Co. LLC), 5.2%, 2028		185,000		83,524
Sabine River Authority, TX, Pollution Control Rev. (TXU Electric Co. LLC), 5.75%, 2030 (b)		155,000		148,825
Sweetwater County, WY, Pollution Control Rev. (Idaho Power Co.), 5.25%, 2026		540,000		588,681
West Feliciana Parish, LA, Pollution Control Rev. (Entergy Gulf States), 6.6%, 2028		270,000		271,050
			$	7,946,807
Utilities - Municipal Owned – 0.1%
Harris County, TX, Cultural Education Facilities Financial Corp., Thermal Utilities Rev. (Teco Project), “A”, 5.25%, 2035	$	140,000	$	151,892
Utilities - Other – 3.7%
California M-S-R Energy Authority Gas Rev., “A”, 7%, 2034	$	155,000	$	188,475
California M-S-R Energy Authority Gas Rev., “A”, 6.5%, 2039		335,000		389,330
Georgia Main Street Natural Gas, Inc., Gas Project Rev., “A”, 5.5%, 2028		335,000		342,320
Georgia Main Street Natural Gas, Inc., Gas Project Rev., “B”, 5%, 2019		325,000		334,545
Indiana Bond Bank Special Program, Gas Rev., “A”, 5.25%, 2018		230,000		253,097
Public Authority for Colorado Energy Natural Gas Purchase Rev., 6.5%, 2038		25,000		28,677
Salt Verde Financial Corp., AZ, Senior Gas Rev., 5%, 2037		705,000		671,703
Tennessee Energy Acquisition Corp., Gas Rev., “A”, 5.25%, 2021		1,710,000		1,778,109
Tennessee Energy Acquisition Corp., Gas Rev., “A”, 5.25%, 2022		270,000		280,233
Tennessee Energy Acquisition Corp., Gas Rev., “A”, 5.25%, 2026		165,000		168,774
Tennessee Energy Acquisition Corp., Gas Rev., “C”, 5%, 2025		240,000		240,725
			$	4,675,988
Water & Sewer Utility Revenue – 3.2%
Atlanta, GA, Water & Wastewater Rev., “A”, 6%, 2022	$	370,000	$	444,504
Birmingham, AL, Waterworks Board Water Rev., “A”, ASSD GTY, 5.125%, 2034		595,000		641,547
Commonwealth of Puerto Rico Aqueduct & Sewer Authority Rev., “A”, 6%, 2038		655,000		709,732
Commonwealth of Puerto Rico Aqueduct & Sewer Authority Rev., “A”, 6%, 2044		135,000		145,275
Detroit, MI, Sewer Disposal System Rev., “B”, AGM, 7.5%, 2033		515,000		633,671

13

MFS High Yield Municipal Trust

PORTFOLIO OF INVESTMENTS (unaudited) 8/31/10 - continued

Issuer	Shares/Par		Value ($)
Municipal Bonds – continued
Water & Sewer Utility Revenue – continued
New York, NY, Municipal Water Finance Authority, Water & Sewer Systems Rev. “DD”, 4.75%, 2035	$	790,000	$	823,899
Surprise, AZ, Municipal Property Corp., 4.9%, 2032		700,000		671,090
			$	4,069,718
Total Municipal Bonds			$	198,633,289
Other Assets, Less Liabilities – 2.0%				2,524,768
Preferred Shares (issued by the Fund) – (59.4)%				(75,000,000	)
Net assets applicable to common shares – 100.0%			$	126,158,057

(a) Non-income producing security.

(b) Mandatory tender date is earlier than stated maturity date.

(c) Refunded bond.

(d) Non-income producing security - in default.

(f) All or a portion of the security has been segregated as collateral for open futures contracts.

(n) Securities exempt from registration under Rule 144A of the Securities Act of 1933. These securities may be sold in the ordinary course of business in transactions exempt from registration, normally to qualified institutional buyers. At period end, the aggregate value of these securities was $3,240,143, representing 2.6% of net assets applicable to common shares.

(z) Restricted securities are not registered under the Securities Act of 1933 and are subject to legal restrictions on resale. These securities generally may be resold in transactions exempt from registration or to the public if the securities are subsequently registered. Disposal of these securities may involve time-consuming negotiations and prompt sale at an acceptable price may be difficult. The fund holds the following restricted securities:

Restricted Securities	Acquisition Date		Cost		Current Market Value
MuniMae TE Bond Subsidiary LLC, 5.8%, 2049		10/04/04	$	1,000,000	$	688,740
Resolution Trust Corp., Pass-Through Certificates, “1993”, 8.5%, 2016		10/17/01-1/14/02		455,481		435,800
Total Restricted Securities					$	1,124,540
% of Net Assets Applicable to Common Shares						0.9	%

The following abbreviations are used in this report and are defined:

COP	Certificate of Participation
ETM	Escrowed to Maturity
FRN	Floating Rate Note. Interest rate resets periodically and may not be the rate reported at period end.
LOC	Letter of Credit
Insurers
AGM	Assured Guaranty Municipal
AMBAC	AMBAC Indemnity Corp.
ASSD GTY	Assured Guaranty Insurance Co.
FGIC	Financial Guaranty Insurance Co.
FHA	Federal Housing Administration
FHLMC	Federal Home Loan Mortgage Corp.
GNMA	Government National Mortgage Assn.
NATL	National Public Finance Guarantee Corp.
PSF	Permanent School Fund
SYNCORA	Syncora Guarantee Inc.

See attached supplemental information. For more information see notes to financial statements as disclosed in the most recent semiannual or annual report.

14

MFS High Yield Municipal Trust

Supplemental Information (Unaudited) 8/31/10

(1) Investment Valuations

Debt instruments and floating rate loans (other than short-term instruments), including restricted debt instruments, are generally valued at an evaluated or composite bid as provided by a third-party pricing service. Short-term instruments with a maturity at issuance of 60 days or less generally are valued at amortized cost, which approximates market value. Futures contracts are generally valued at last posted settlement price as provided by a third-party pricing service on the market on which they are primarily traded. Futures contracts for which there were no trades that day for a particular position are generally valued at the closing bid quotation as provided by a third-party pricing service on the market on which such futures contracts are primarily traded. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net assets value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. Other financial instruments are derivative instruments not reflected in total investments, such as futures, forwards, swap contracts, and written options. The following is a summary of the levels used as of August 31, 2010 in valuing the fund’s assets or liabilities:

	Level 1			Level 2		Level 3		Total
Investments at Value
Municipal Bonds	$	—		$	198,633,289	$	—	$	198,633,289
Other Financial Instruments
Futures	$	(72,018	)	$	—	$	—	$	(72,018	)

For further information regarding security characteristics, see the Portfolio of Investments.

(2) Portfolio Securities

The cost and unrealized appreciation and depreciation in the value of the investments owned by the fund, as computed on a federal income tax basis, are as follows:

Aggregate cost	$	197,373,441
Gross unrealized appreciation	$	13,159,428
Gross unrealized depreciation		(11,899,580	)
Net unrealized appreciation (depreciation)	$	1,259,848

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

15

MFS High Yield Municipal Trust

Supplemental Information (Unaudited) 8/31/10 - continued

(3) Derivative Contracts at 8/31/10

Futures Contracts Outstanding at 8/31/10

Description	Currency		Contracts		Value		Expiration Date		Unrealized Appreciation (Depreciation)
Liability Derivatives
Interest Rate Futures
U.S. Treasury Note 10 yr (Short)		USD		238		29,898,750		Dec-2010	$	(58,931	)
U.S. Treasury Bond 30 yr (Short)		USD		32		4,321,000		Dec-2010		(13,087	)
									$	(72,018	)

At August 31, 2010, the fund had sufficient cash and/or other liquid securities to cover any commitments under these derivative contracts.

16

ITEM 2. CONTROLS AND PROCEDURES.

(a) Based upon their evaluation of the effectiveness of the registrant’s disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940 (the “Act”)) as conducted within 90 days of the filing date of this Form N-Q, the registrant’s principal financial officer and principal executive officer have concluded that those disclosure controls and procedures provide reasonable assurance that the material information required to be disclosed by the registrant on this report is recorded, processed, summarized and reported within the time periods specified in the Securities and Exchange Commission’s rules and forms.

(b) There were no changes in the registrant’s internal controls over financial reporting (as defined in Rule 30a-3(d) under the Act) that occurred during the registrant’s last fiscal quarter that have materially affected, or are reasonably likely to materially affect, the registrant’s internal control over financial reporting.

ITEM 3. EXHIBITS.

File as exhibits as part of this Form a separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the Act (17 CFR 270.30a-2): Attached hereto.

Notice

A copy of the Agreement and Declaration of Trust, as amended, of the Registrant is on file with the Secretary of State of The Commonwealth of Massachusetts and notice is hereby given that this instrument is executed on behalf of the Registrant by an officer of the Registrant as an officer and not individually and the obligations of or arising out of this instrument are not binding upon any of the Trustees or shareholders individually, but are binding only upon the assets and property of the respective constituent series of the Registrant.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Registrant: MFS HIGH YIELD MUNICIPAL TRUST

By (Signature and Title)*	MARIA F. DWYER
	Maria F. Dwyer, President

Date: October 18, 2010

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)*	MARIA F. DWYER
	Maria F. Dwyer, President (Principal Executive Officer)

Date: October 18, 2010

By (Signature and Title)*	JOHN M. CORCORAN
	John M. Corcoran, Treasurer (Principal Financial Officer and Accounting Officer)

Date: October 18, 2010

* Print name and title of each signing officer under his or her signature.

EX-99.CERT

EX-99.CERT

MFS HIGH YIELD MUNICIPAL TRUST

CERTIFICATION

I, John M. Corcoran, certify that:

1. I have reviewed this report on Form N-Q of MFS High Yield Municipal Trust;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the schedules of investments included in this report fairly present in all material respects the investments of the registrant as of the end of the fiscal quarter for which the report is filed;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the Investment Company Act of 1940) for the registrant and have:

a. Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b. Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c. Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of a date within 90 days prior to the filing date of this report, based on such evaluation; and

d. Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a. All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize, and report financial information; and

b. Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: October 18, 2010	JOHN M. CORCORAN
	John M. Corcoran
	Treasurer (Principal Financial Officer and Accounting Officer)

EX-99.CERT

MFS HIGH YIELD MUNICIPAL TRUST

CERTIFICATION

I, Maria F. Dwyer, certify that:

1. I have reviewed this report on Form N-Q of MFS High Yield Municipal Trust;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the schedules of investments included in this report fairly present in all material respects the investments of the registrant as of the end of the fiscal quarter for which the report is filed;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the Investment Company Act of 1940) for the registrant and have:

a. Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b. Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c. Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of a date within 90 days prior to the filing date of this report, based on such evaluation; and

d. Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a. All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize, and report financial information; and

b. Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: October 18, 2010	MARIA F. DWYER
	Maria F. Dwyer
	President (Principal Executive Officer)