UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM N-Q

QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS OF REGISTERED
MANAGEMENT INVESTMENT COMPANY

Investment Company Act file number 811-21178

Name of Fund: BlackRock Insured Municipal Income Trust (BYM)

Fund Address: 100 Bellevue Parkway, Wilmington, DE 19809

Name and address of agent for service: Donald C. Burke, Chief Executive Officer, BlackRock Insured Municipal Income Trust, 800 Scudders Mill Road, Plainsboro, NJ, 08536.
Mailing address: P.O. Box 9011, Princeton, NJ, 08543-9011

Registrant’s telephone number, including area code: (800) 882-0052, Option 4

Date of fiscal year end: 08/31/2008

Date of reporting period: 09/01/2007 – 11/30/2007

Item 1 – Schedule of Investments


BlackRock Insured Municipal Income Trust    
Schedule of Investments as of November 30, 2007 (Unaudited)  
(In Thousands)
    Face        
State   Amount     Municipal Bonds  
Value
Alabama - 0.7% $ 2,800   Jefferson County, Alabama, Limited Obligation School Warrants, Series A, 4.75% due 1/01/2025 $    2,819
Arizona - 5.5%   2,500   Downtown Phoenix Hotel Corporation, Arizona, Revenue Bonds, Senior Series A, 5% due 7/01/2040 (b)   2,545
    15,000   Phoenix, Arizona, Civic Improvement Corporation, Excise Tax Revenue Bonds    
        (Civic Plaza Expansion Project), Sub-Series A, 5% due 7/01/2041 (b)   15,438
    4,000   Salt Verde Financial Corporation, Arizona, Senior Gas Revenue Bonds, 5% due 12/01/2037   3,832
California - 33.3%   2,000   Arcadia, California, Unified School District, Capital Appreciation, GO (Election of 2006), Series A,    
        4.96 % due 8/01/2039 (c)(i)   392
    10,100   California Infrastructure and Economic Development Bank, First Lien Revenue Bonds    
        (Bay Area Toll Bridges Retrofit), Series A, 5% due 1/01/2028 (a)(f)   11,174
    14,000   California State Department of Water Resources, Power Supply Revenue Bonds, Series A, 5.375% due 5/01/2012 (f)   15,331
    4,200   Coast Community College District, California, GO (Election of 2002), Series C, 5.392% due 8/01/2036 (c)(i)   921
    1,100   Fresno, California, Unified School District, GO (Election of 2001), Series E, 5% due 8/01/2030 (c)   1,152
    6,500   Golden State Tobacco Securitization Corporation of California, Tobacco Settlement Revenue Bonds, Series A-1,    
        6.625% due 6/01/2013 (f)   7,516
    14,500   Golden State Tobacco Securitization Corporation of California, Tobacco Settlement Revenue Bonds, Series A-1, 6.75%    
        due 6/01/2013 (f)   16,858
    4,000   Los Angeles, California, Municipal Improvement Corporation, Lease Revenue Bonds, Series B1,    
        4.75% due 8/01/2037 (b)   4,000
    17,500   Metropolitan Water District of Southern California, Waterworks Revenue Bonds, Series B-1, 5% due 10/01/2033 (b)   17,988
    500   Rancho Cucamonga, California, Redevelopment Agency, Tax Allocation Refunding Bonds    
        (Rancho Redevelopment Project), Series A, 5% due 9/01/2034 (e)   512
    2,700   Sacramento, California, Unified School District, GO (Election of 2002), 5% due 7/01/2030 (e)   2,814
    15,000   San Francisco, California, City and County Public Utilities Commission, Water Revenue Refunding Bonds, Series A,    
        5% due 11/01/2031 (c)   15,380
    53,000   San Joaquin Hills, California, Transportation Corridor Agency, Toll Road Revenue Refunding Bonds, Series A,    
        5.45% due 1/15/2031 (e)(i)   16,651
    10,000   University of California Revenue Bonds, Series C, 4.75% due 5/15/2037 (e)   10,094
    10,000   University of California Revenue Bonds, Series O, 5% due 9/01/2010 (b)(f)   10,562
District of Columbia - 3.0%       2,000   District of Columbia, GO, Series A, 4.75% due 6/01/2036 (b)   2,015
    9,500   District of Columbia Tobacco Settlement Financing Corporation, Asset-Backed Revenue Refunding Bonds,    
        6.75% due 5/15/2040   9,723
Portfolio Abbreviations
To simplify the listings of Blackrock Insured Municipal Income Trust's portfolio
holdings in the Schedule of Investments, we have abbreviated the names of many
securities according to the list below.
AMT Alternative Minimum Tax (subject to)
EDA Economic Development Authority
GO General Obligation Bonds
IDA Industrial Development Authority
PCR Pollution Control Revenue Bonds

1

BlackRock Insured Municipal Income Trust    
Schedule of Investments as of November 30, 2007 (Unaudited)  
(In Thousands)
    Face          
State   Amount   Municipal Bonds  
Value
Florida - 7.3% $ 1,650   Highlands County, Florida, Health Facilities Authority, Hospital Revenue Bonds (Adventist Health System), Series C,    
        5.25% due 11/15/2036 $    1,666
    2,000   Jacksonville, Florida, Health Facilities Authority, Hospital Revenue Bonds (Baptist Medical Center Project),    
        5% due 8/15/2037 (c)   2,024
    9,500   Miami-Dade County, Florida, Aviation Revenue Bonds (Miami International Airport), Series B, 5% due 10/01/2037 (b)   9,703
    25,520   Miami-Dade County, Florida, Special Obligation Revenue Bonds, Sub-Series A, 5.25% due 10/01/2038 (e)(i)   5,194
    4,225   Miami-Dade County, Florida, Transit Sales Surtax Revenue Bonds, 4.75% due 7/01/2036 (h)   4,228
    1,000   Miami, Florida, Special Obligation Revenue Bonds (Street and Sidewalk Improvement Program), 5% due 1/01/2037 (e)   1,017
    5,000   Orange County, Florida, Tourist Development, Tax Revenue Refunding Bonds, 4.75% due 10/01/2032 (h)   5,002
Georgia - 3.5%   2,000   Atlanta, Georgia, Water and Wastewater Revenue Bonds, 5% due 11/01/2034 (c)   2,064
    3,235   Atlanta, Georgia, Water and Wastewater Revenue Bonds, 5% due 11/01/2037 (c)   3,334
    8,555   Atlanta, Georgia, Water and Wastewater Revenue Refunding Bonds, Series A, 5% due 11/01/2038 (b)   8,630
Illinois - 18.7%   14,875   Bolingbrook, Illinois, GO, Refunding, Series A, 4.75% due 1/01/2038 (e)   14,990
    11,550   Chicago, Illinois, Special Transportation Revenue Bonds, 5.25% due 1/01/2027 (a)(f)   12,094
    6,165   Illinois Municipal Electric Agency, Power Supply Revenue Bonds, 4.50% due 2/01/2035 (b)   5,886
    10,000   Illinois Municipal Electric Agency, Power Supply Revenue Bonds, Series A, 5% due 2/01/2035 (b)   10,303
    24,010   Metropolitan Pier and Exposition Authority, Illinois, Dedicated State Tax Revenue Bonds    
        (McCormick Place Expansion), Series A, 5% due 12/15/2028 (e)   24,783
    15,000   Metropolitan Pier and Exposition Authority, Illinois, Dedicated State Tax Revenue Refunding Bonds    
        (McCormick Place Expansion), 5.50% due 6/15/2028 (e)(i)   5,684
Indiana - 1.2%   4,725   Indiana Municipal Power Agency, Power Supply System Revenue Bonds, Series A, 4.50% due 1/01/2032 (a)   4,543
Kentucky - 1.6%   6,250   Kentucky State Municipal Power Agency, Power System Revenue Bonds (Prairie State Project), Series A,    
        5% due 9/01/2037 (e)   6,509
Louisiana - 4.5%   5,450   Louisiana State, Gas and Fuels Tax Revenue Bonds, Series A, 5% due 5/01/2035 (b)   5,589
    12,100   Louisiana State, Gas and Fuels Tax Revenue Bonds, Series A, 4.75% due 5/01/2039 (c)   12,100
Massachusetts - 8.8%            10,190   Massachusetts Bay Transportation Authority, Sales Tax Revenue Refunding Bonds, Senior Series A-2,    
        4.80% due 7/01/2032 (i)   2,994
    3,200   Massachusetts Bay Transportation Authority, Sales Tax Revenue Refunding Bonds, Senior Series A-2,    
        5.12% due 7/01/2035 (i)   806
    625   Massachusetts State Health and Educational Facilities Authority Revenue Bonds (Lahey Clinic Medical Center),    
        Series D, 5.25% due 8/15/2037   632
    24,000   Massachusetts State Turnpike Authority, Metropolitan Highway System Revenue Refunding Bonds, Sub-Series A, 5%    
        due 1/01/2039 (a)   24,202
    5,985   Massachusetts State Water Resource Authority, General Revenue Refunding Bonds, Series A, 5% due 8/01/2041   6,180
Michigan - 1.5%   1,000   Detroit, Michigan, Water Supply System Revenue Bonds, Senior Lien, Series A, 5% due 7/01/2030 (b)   1,017
    5,000   Michigan State Hospital Finance Authority, Revenue Refunding Bonds (Henry Ford Health System), Series A,    
        5% due 11/15/2038   4,908
Nebraska - 1.8%   2,780   Omaha Public Power District, Nebraska, Electric System Revenue Bonds, Series A, 4.75% due 2/01/2044   2,756
    4,000   Public Power Generation Agency, Nebraska, Revenue Bonds (Whelan Energy Center Unit 2), Series A,    
        5% due 1/01/2032 (a)   4,175

2

BlackRock Insured Municipal Income Trust    
Schedule of Investments as of November 30, 2007 (Unaudited)  
(In Thousands)
    Face        
State   Amount     Municipal Bonds  
Value
Nevada - 7.4% $ 6,000   Reno, Nevada, Sales and Room Tax Revenue Refunding Bonds    
        (ReTrac-Reno Transportation Rail Access Corridor Project), Senior Lien, 5.125% due 6/01/2012 (a)(f) $    6,452
    10,000   Truckee Meadows, Nevada, Water Authority, Water Revenue Bonds, Series A, 5% due 7/01/2011 (c)(f)   10,581
    6,500   Truckee Meadows, Nevada, Water Authority, Water Revenue Bonds, Series A, 5.125% due 7/01/2011 (c)(f)   6,905
    5,000   Truckee Meadows, Nevada, Water Authority, Water Revenue Bonds, Series A, 5.25% due 7/01/2011 (c)(f)   5,332
New York - 3.2%   7,000   Metropolitan Transportation Authority, New York, Dedicated Tax Fund Revenue Bonds, Series A,    
        5% due 11/15/2031 (e)   7,324
    5,000   New York City, New York, Trust for Cultural Resources Revenue Refunding Bonds    
        (American Museum of Natural History), Series A, 5% due 7/01/2044 (e)   5,141
Pennsylvania - 4.4%   2,500   Lebanon County, Pennsylvania, Health Facilities Authority, Hospital Revenue Bonds    
        (Good Samaritan Hospital Project), 6% due 11/15/2035   2,583
    5,200   Philadelphia, Pennsylvania, Gas Works Revenue Bonds, 3rd Series, 5.125% due 8/01/2011 (c)(f)   5,527
    9,000   Philadelphia, Pennsylvania, Gas Works Revenue Refunding Bonds, 1998 General Ordinance, 7th Series,    
        5% due 10/01/2032 (a)   9,318
South Carolina - 7.4%       5,000   South Carolina State Public Service Authority Revenue Bonds, Series B, 5.50% due 1/01/2012 (c)(f)   5,419
    10,000   South Carolina Transportation Infrastructure Bank Revenue Bonds, Junior Lien, Series B, 5.125%    
        due 10/01/2011(a)(f)   10,656
    12,750   South Carolina Transportation Infrastructure Bank Revenue Bonds, Series A, 5% due 10/01/2033 (a)   13,067
Tennessee - 5.8%   11,705   Knox County, Tennessee, Health, Educational and Housing Facilities Board, Hospital Facilities Revenue Refunding    
        Bonds (Covenant Health), Series A, 5.84% due 1/01/2022 (c)(i)   5,505
    9,260   Knox County, Tennessee, Health, Educational and Housing Facilities Board, Hospital Facilities Revenue Refunding    
        Bonds (Covenant Health), Series A, 5.88% due 1/01/2023 (c)(i)   4,083
    8,500   Knox County, Tennessee, Health, Educational and Housing Facilities Board, Hospital Facilities Revenue Refunding    
        Bonds (Covenant Health), Series A, 5.90% due 1/01/2024 (c)(i)   3,523
    6,850   Knox County, Tennessee, Health, Educational and Housing Facilities Board, Hospital Facilities Revenue Refunding    
        Bonds (Covenant Health), Series A, 5.91% due 1/01/2025 (c)(i)   2,673
    5,000   Knox County, Tennessee, Health, Educational and Housing Facilities Board, Hospital Facilities Revenue Refunding    
        Bonds (Covenant Health), Series A, 5.93% due 1/01/2026 (c)(i)   1,830
    10,000   Knox County, Tennessee, Health, Educational and Housing Facilities Board, Hospital Facilities Revenue Refunding    
        Bonds (Covenant Health), Series A, 5.07% due 1/01/2041 (c)(i)   1,650
    3,400   Tennessee Energy Acquisition Corporation, Gas Revenue Bonds, Series A, 5.25% due 9/01/2026   3,432
Texas - 25.9%   10,030   Coppell, Texas, Independent School District, GO, Refunding, 5.64% due 8/15/2030 (i)   3,371
    2,350   Dallas, Texas, Area Rapid Transit Revenue Refunding Bonds, Senior Lien, 5% due 12/01/2011 (a)(f)   2,501
    5,785   Harris County-Houston Sports Authority, Texas, Revenue Refunding Bonds, Junior Lien, Series H,    
        5.81% due 11/15/2038 (e)(i)   1,113
    6,160   Harris County-Houston Sports Authority, Texas, Revenue Refunding Bonds, Junior Lien, Series H,    
        5.83% due 11/15/2039 (e)(i)   1,113
    26,890   Harris County-Houston Sports Authority, Texas, Revenue Refunding Bonds, Third Lien, Series A-3,    
        5.98% due 11/15/2038 (e)(i)   5,033
    27,675   Harris County-Houston Sports Authority, Texas, Revenue Refunding Bonds, Third Lien, Series A-3,    
        5.99% due 11/15/2039 (e)(i)   4,885

3

BlackRock Insured Municipal Income Trust    
Schedule of Investments as of November 30, 2007 (Unaudited)  
(In Thousands)
    Face            
State   Amount   Municipal Bonds  
Value
 
 
$
7,485   Harris County, Texas, GO, Refunding, 5.49% due 8/15/2025 (e)(i) $ 3,265  
    10,915   Harris County, Texas, GO, Refunding, 5.52% due 8/15/2028 (e)(i)   4,071  
    5,510   Harris County, Texas, Toll Road Revenue Refunding Bonds, Senior Lien, 5% due 8/15/2030 (c)   5,656  
    5,315   Lewisville, Texas, Independent School District, Capital Appreciation and School Building, GO, Refunding,      
        4.67% due 8/15/2024 (b)(i)   2,290  
    1,045   Montgomery County, Texas, Municipal Utility District Number 46, Waterworks and Sewer System, GO,      
        4.75% due 3/01/2030 (e)   1,055  
    1,100   North Texas Thruway Authority, Dallas North Thruway System Revenue Bonds, Series A, 5% due 1/01/2035 (c)   1,137  
    9,500   Northside, Texas, Independent School District, GO, 5.125% due 6/15/2029   9,911  
    3,000   Pearland, Texas, GO, Refunding, 4.75% due 3/01/2029 (b)   3,039  
    9,350   San Antonio, Texas, Water System Revenue Refunding Bonds, 5.125% due 5/15/2029 (b)   9,728  
    10,000   San Antonio, Texas, Water System Revenue Refunding Bonds, 5.125% due 5/15/2034 (b)   10,371  
    30,145   Texas State Turnpike Authority, Central Texas Turnpike System Revenue Bonds, First Tier, Series A,      
        5% due 8/15/2042 (a)   30,420  
    3,000   Tyler, Texas, Health Facilities Development Corporation, Hospital Revenue Bonds      
        (Mother Frances Hospital Regional Health Care Center), 6% due 7/01/2012 (f)   3,333  
Virginia - 1.9%   4,000   Chesterfield County, Virginia, IDA, PCR, Refunding (Virginia Electric and Power Company), Series B,      
        5.875% due 6/01/2017   4,247  
    3,000   Chesterfield County, Virginia, IDA, PCR (Virginia Electric and Power Company), Series A, 5.875% due 6/01/2017   3,173  
Washington - 8.6%   9,610   Central Washington University, System Revenue Bonds, 5% due 5/01/2034 (b)   9,907  
    3,655   Chelan County, Washington, Public Utility District Number 001, Consolidated Revenue Bonds (Chelan Hydro System),      
        AMT, Series C, 5.125% due 7/01/2033 (a)   3,758  
    2,200   King County, Washington, Sewer Revenue Refunding Bonds, 5% due 1/01/2036 (c)   2,290  
    4,500   Port of Seattle, Washington, Revenue Bonds, Series A, 5% due 4/01/2031 (b)   4,606  
    5,000   Seattle, Washington, GO, Series F, 5.125% due 12/15/2008 (e)(f)   5,090  
    6,380   Washington State, GO, Series 02-A, 5% due 7/01/2025 (c)   6,600  
    2,000   Washington State Health Care Facilities Authority, Revenue Refunding Bonds (Providence Health System), Series A,      
        4.50% due 10/01/2035 (b)   1,882  
West Virginia - 0.3%       1,295   West Virginia EDA, Lease Revenue Bonds (Correctional, Juvenile and Public Safety Facilities), Series A,      
        5% due 6/01/2029 (e)   1,339  
        Total Municipal Bonds (Cost - $589,111) - 156.3%   616,915  
    Shares          
    Held   Short-Term Securities      
    2,000   Merrill Lynch Institutional Tax-Exempt Fund, 3.43% (d)(g)   2,000  
        Total Short-Term Securities (Cost - $2,000) - 0.5%   2,000  
        Total Investments (Cost - $591,111*) - 156.8%   618,915  
        Other Assets Less Liabilities - 1.2%   4,851  
        Preferred Shares, at Redemption Value - (58.0%)   (229,133 )
        Net Assets Applicable to Common Shares - 100.0% $ 394,633  

4

BlackRock Insured Municipal Income Trust    
Schedule of Investments as of November 30, 2007 (Unaudited)  
(In Thousands)
*     

The cost and unrealized appreciation (depreciation) of investments as of November 30, 2007, as computed for federal income tax purposes, were as follows:
Aggregate cost $ 591,111  
Gross unrealized appreciation $                      28,827  
Gross unrealized depreciation   (1,023 )
Net unrealized appreciation $ 27,804  
(a)   

AMBAC Insured.
(b)

FGIC Insured.
(c)

FSA Insured.
(d)

Investments in companies considered to be an affiliate of the Trust, for purposes of Section 2(a)(3) of the Investment Company Act of 1940, were as follows:
Affiliate
Net Activity
Dividend Income
Merrill Lynch Institutional Tax-Exempt Fund
(300)
$21
(e)    MBIA Insured.
(f) Prerefunded. 
(g) Represents the current yield as of November 30, 2007.
(h) XL Capital Insured. 
(i) Represents a zero coupon bond; the interest rate shown reflects the effective yield at the time of purchase. 
• Forward interest rate swaps outstanding as of November 30, 2007 were as follows:
      Notional         Unrealized  
      Amount     Depreciation  
Pay a fixed rate of 3.635% and receive a floating rate based on 1-week              
(SIFMA) Municipal Swap Index rate              
Broker, Citibank N.A.              
Expires March 2023   $ 20,000   $ (165 )
Pay a fixed rate of 3.905% and receive a floating rate based on 1-week              
(SIFMA) Municipal Swap Index rate              
Broker, JPMorgan Chase              
Expires January 2028   $ 15,000     (437 )
Pay a fixed rate of 4.026% and receive a floating rate based on 1-week              
(SIFMA) Municipal Swap Index rate              
Broker, Citibank N.A.              
Expires December 2032   $ 7,500     (328 )
Pay a fixed rate of 4.065% and receive a floating rate based on 1-week              
(SIFMA) Municipal Swap Index rate              
Broker, Citibank N.A.              
Expires December 2037   $ 16,500     (793 )
          $ (1,723 )

5

Item 2 – Controls and Procedures

2(a) –     The registrant’s principal executive and principal financial officers or persons performing similar functions have concluded that the registrant’s disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940, as amended (the “1940 Act”)) are effective as of a date within 90 days of the filing of this report based on the evaluation of these controls and procedures required by Rule 30a-3(b) under the 1940 Act and Rule 13a-15(b) under the Securities and Exchange Act of 1934, as amended.

2(b) –     There were no changes in the registrant’s internal control over financial reporting (as defined in Rule 30a-3(d) under the 1940 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

Certifications – Attached hereto

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.

BlackRock Insured Municipal Income Trust

By:       /s/ Donald C. Burke
  Donald C. Burke,
  Chief Executive Officer of
  BlackRock Insured Municipal Income Trust

Date: January 16, 2008

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:       /s/ Donald C. Burke
  Donald C. Burke,
  Chief Executive Officer (principal executive officer) of
  BlackRock Insured Municipal Income Trust

Date: January 16, 2008

By:       /s/ Neal J. Andrews
  Neal J. Andrews,
  Chief Financial Officer (principal financial officer) of
  BlackRock Insured Municipal Income Trust

Date: January 16, 2008