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          

          BlackRock Insured Municipal Income Trust          
(Exact name of registrant as specified in charter)

100 Bellevue Parkway, Wilmington, DE 
19809 
(Address of principal executive offices)  (Zip code) 


Robert S. Kapito, President 
BlackRock Insured Municipal Income Trust
40 East 52nd Street, New York, NY 10022 
(Name and address of agent for service) 

Registrant’s telephone number, including area code:      888-825-2257          

Date of fiscal year end:      August 31, 2007   
Date of reporting period:
     November 30, 2006   


Item 1. Schedule of Investments.

The Registrant’s unaudited schedule of investments as of the close of the reporting period pursuant to Rule 30b1-5 under the Investment Company Act of 1940 is as follows:

PORTFOLIO OF INVESTMENTS (unaudited)         
NOVEMBER 30, 2006         
BlackRock Insured Municipal Income Trust (BYM)         
(Percentage of Net Assets)         
 
 
 
   
Principal 
           
   
Amount 
   
Option Call 
     
Rating1 
 
(000) 
  Description  Provisions2   
Value 
 
        LONG-TERM INVESTMENTS—149.3%         
        Arizona—2.6%         
AAA    $      10,000    Phoenix Civic Impt. Corp. RB, Civic Plaza Expansion Proj., 5.00%, 7/01/41, FGIC  07/15 @ 100  $  10,645,500   
        California—31.8%         
Aaa    14,0003   Dept. of Wtr. Res., Cash Flow Mgt. Elec., Pwr. & Lt. RB, Ser. A, 5.375%, 5/01/12  N/A    15,444,940   
        Golden St. Tobacco Sec. Corp., Misc. Purposes Tobacco Settlement Funded RB,         
BBB    6,500       Ser. A-1, 6.625%, 6/01/40  06/13 @ 100    7,408,635   
BBB    14,500       Ser. A-1, 6.75%, 6/01/39  06/13 @ 100    16,673,985   
AAA    10,1003   Infrastructure & Econ Dev. RB Bay Area Toll Brdgs. Proj., Ser. A, 5.00%, 1/01/28,         
           AMBAC  N/A    11,654,996   
AAA    17,500    Met. Wtr. Dist. Southern California, Wtr. Util. Impvts. RB, Ser. B-1, 5.00%, 10/01/33,         
           FGIC  10/13 @ 100    18,622,800   
AAA    2,700    Sacramento City Sch. Dist. Election of 2002 GO, 5.00%, 7/01/30, MBIA  07/15 @ 100    2,904,660   
AAA    15,000    San Francisco City & Cnty. Pub. Utils. Comm., Wtr. Util. Impvts. RB, Ser. A, 5.00%,         
           11/01/31, FSA  11/11 @ 100    15,683,850   
AAA    53,000    San Joaquin Hills Transp. Corridor Agcy., Hwy. Tolls RB, Ser. A, Zero Coupon, 1/15/31,         
           MBIA  No Opt. Call    18,900,330   
        Univ. of California, Univ. & Coll. Impvts. RB,         
AAA    10,000       Ser. C, 4.75%, 5/15/37, MBIA  05/13 @ 101    10,400,200   
AAA    3,330       Ser. G, 4.75%, 5/15/31, MBIA  05/13 @ 101    3,469,993   
AAA    10,910       Ser. O, 5.00%, 9/01/28, FGIC  09/10 @ 101    11,395,604   
              132,559,993   
        District of Columbia—2.5%         
BBB    9,500    Tobacco Settlement Fin. Corp., Tobacco Settlement Funded RB, 6.75%, 5/15/40  05/11 @ 101    10,452,660   
        Florida—6.4%         
        Cnty. of Miami-Dade,         
AAA    9,500       Port, Arpt. & Marina Impvts. RB, Miami Intl. Arpt. Proj., Ser. B, 5.00%, 10/01/37, FGIC  10/14 @ 100    10,066,295   
AAA    25,520       Recreational Fac. Impvts. Misc. RB, Cap. Apprec. Proj., Ser. A, Zero Coupon, 10/01/38,         
           MBIA  10/15 @ 30.363    5,211,439   
AAA    1,880    JEA, Wtr. Util. RB, Ser. A, 4.75%, 10/01/36, MBIA  04/11 @ 100    1,926,493   
AAA    5,485    Orange Cnty. Tourist Dev., Sales Tax RB, 4.75%, 10/01/32, XLCA  10/16 @ 100    5,704,674   
AAA    3,600    Tampa Wtr. & Swr., Wtr. Util. Impvts. RB, 4.625%, 10/01/36, MBIA  10/16 @ 100    3,687,048   
              26,595,949   
        Georgia—3.9%         
        City of Atlanta,         
AAA    800       Port, Arpt. & Marina Impvts. RB, Ser. J, 5.00%, 1/01/34, FSA  01/15 @ 100    849,104   
AAA    9,555       Wtr. RB, Ser. A, 5.00%, 11/01/38, FGIC  05/09 @ 101    9,806,297   
AAA    2,000       Wtr. Util. Impvts. RB, 5.00%, 11/01/34, FSA  11/14 @ 100    2,131,760   
AAA    3,235       Wtr. Util. Impvts. RB, 5.00%, 11/01/37, FSA  11/14 @ 100    3,445,857   
              16,233,018   
        Illinois—15.7%         
AAA    11,550    Chicago Spec. Transp., Hwy. Impvts. RB, 5.25%, 1/01/27, AMBAC  01/11 @ 100    12,326,738   
        Met. Pier & Exposition Auth., Ded. St. Tax RB, McCormick Place Expansion Proj.,         
AAA    24,010       Ser. A, 5.00%, 12/15/28, MBIA  06/12 @ 101    25,379,530   
AAA    15,000       Ser. B, Zero Coupon, 6/15/28, MBIA  No Opt. Call    6,062,550   
AAA    6,165    Mun. Elec. Agcy. Pwr. Sply., Elec., Pwr. & Lt. RB, 4.50%, 2/01/35, FGIC  02/16 @ 100    6,233,986   
AAA    14,875    Vlg. of Bolingbrook GO, Ser. A, 4.75%, 1/01/38, MBIA  01/15 @ 100    15,430,433   
              65,433,237   
        Indiana—1.1%         
AAA    4,725    Mun. Pwr. Agcy. Pwr. Sply. Sys., Elec., Pwr. & Lt. RB, Ser. A, 4.50%, 1/01/32, AMBAC  01/16 @ 100    4,784,630   
        Kansas—0.4%         
A    1,750    Univ. Hosp. Auth., Refdg. & Impvt. RB, Univ. of Kansas Hlth. Sys. Proj., 5.00%, 9/01/36  09/16 @ 100    1,837,833   
        Louisiana—3.9%         
AAA    10,000    Hwy. Impvt. Sales Tax RB, Ser. A, 4.75%, 5/01/39, FSA  05/16 @ 100    10,392,300   

1


BlackRock Insured Municipal Income Trust (BYM) (continued)         
(Percentage of Net Assets)         
 
 
 
   
Principal 
           
   
Amount 
   
Option Call 
     
Rating1 
 
(000) 
 
Description 
Provisions2   
Value 
 
        Louisiana—(cont'd)         
AAA    $      5,450    Hwy. Impvt. Fuel Sales Tax RB, Ser. A, 5.00%, 5/01/35, FGIC 
05/15 @ 100  
$
5,824,088   
              16,216,388   
        Massachusetts—7.5%         
AAA    24,000    Tpke. Auth. Met. Hwy. Sys., Hwy. Tolls RB, Ser. A, 5.00%, 1/01/39, AMBAC  01/09 @ 101    24,710,400   
AA    5,985    Wtr. Res. Auth., Wtr. RB, Ser. A, 5.00%, 8/01/41  08/16 @ 100    6,401,257   
              31,111,657   
        Michigan—1.3%         
AAA    5,000    Detroit, Sewer Impvts. RB, Ser. A, 5.00%, 7/01/32, FSA  07/13 @ 100    5,272,000   
        Missouri—1.0%         
AAA    4,100    Joint Mun. Elec. Util. Comm., Elec., Pwr. & Lt. Impvts. RB, Plum Point Proj., 4.60%,         
           1/01/36, MBIA  01/16 @ 100    4,185,362   
        Nebraska—1.1%         
AA    4,280    Omaha Pub. Pwr. Dist., Elec., Pwr. & Lt. RB, Ser. A, 4.75%, 2/01/44  02/14 @ 100    4,394,832   
        Nevada—9.5%         
AAA    6,0003   Reno, Misc. Taxes RB, Reno Trans. Proj., 5.125%, 6/01/12, AMBAC  N/A    6,453,060   
        Truckee Meadows Wtr. Auth.,         
AAA    10,000       Refdg. Wtr. RB, 4.875%, 7/01/34, XLCA  07/16 @ 100    10,455,500   
AAA    10,000       Wtr. Util. Impvts. RB, Ser. A, 5.00%, 7/01/25, FSA  07/11 @ 100    10,478,900   
AAA    6,500       Wtr. Util. Impvts. RB, Ser. A, 5.125%, 7/01/30, FSA  07/11 @ 100    6,836,765   
AAA    5,0003      Wtr. Util. Impvts. RB, Ser. A, 5.25%, 7/01/11, FSA  N/A    5,356,650   
              39,580,875   
        New York—4.4%         
AAA    7,305    New York City Mun. Wtr. Fin. Auth., Wtr. RB, Ser. C, 5.00%, 6/15/35, AMBAC  06/14 @ 100    7,781,286   
AAA    10,000    New York City Trust Cultural Rec. Recovery RB, American Museum of Natural History         
           Proj., Ser. A, 5.00%, 7/01/44, MBIA  07/14 @ 100    10,606,100   
              18,387,386   
        Ohio—3.0%         
AAA    12,000    Air Qual. Dev. Auth., Rec. Recovery PCRB, Dayton Pwr. & Lt. Co. Proj., 4.80%, 1/01/34,         
           FGIC  07/15 @ 100    12,496,560   
        Pennsylvania—2.6%         
BBB    5,000    Lebanon Cnty. Hlth. Facs. Auth., Hlth., Hosp. & Nursing Home Impvts. RB, Good         
           Samaritan Hosp. Proj., 6.00%, 11/15/35  11/12 @ 101    5,462,300   
AAA    5,2003   Philadelphia Gas Wks., Natural Gas Util. Impvts. RB, Ser. 3, 5.125%, 8/01/11, FSA  N/A    5,551,624   
              11,013,924   
        South Carolina—7.7%         
AAA    5,0003   Pub. Svc. Auth., Elec. Pwr. & Lt. RB, Ser. B, 5.50%, 1/01/12, FSA  N/A    5,447,450   
        Transp. Infrastructure Bank,         
AAA    12,750       Fuel Sales Tax RB, Ser. A, 5.00%, 10/01/33, AMBAC  10/12 @ 100    13,468,335   
AAA    12,660       Trans. Impvts. RB, Ser. B, 5.125%, 10/01/26, AMBAC  10/11 @ 100    13,376,809   
              32,292,594   
        Tennessee—4.1%         
       
Knox Cnty. Hlth. Edl. & Hsg. Facs. Brd., Hlth., Hosp. & Nursing Home RB, Covenant Hlth. Proj.,
       
AAA    11,705       Ser. A, Zero Coupon, 1/01/22, FSA  01/13 @ 59.566    5,349,770   
AAA    9,260       Ser. A, Zero Coupon, 1/01/23, FSA  01/13 @ 56.016    3,975,318   
AAA    8,500       Ser. A, Zero Coupon, 1/01/24, FSA  01/13 @ 52.749    3,432,130   
AAA    6,850       Ser. A, Zero Coupon, 1/01/25, FSA  01/13 @ 49.712    2,603,548   
AAA    5,000       Ser. A, Zero Coupon, 1/01/26, FSA  01/13 @ 46.781    1,784,100   
              17,144,866   
        Texas—26.0%         
        City of San Antonio, Wtr. RB,         
AAA    9,350       5.125%, 5/15/29, FGIC  05/14 @ 100    10,024,229   
AAA    10,000       5.125%, 5/15/34, FGIC  05/14 @ 100    10,694,500   
        Cnty. of Harris, Ad Valorem Ppty. Tax GO,         
AAA    7,485       Zero Coupon, 8/15/25, MBIA  No Opt. Call    3,364,582   
AAA    10,915       Zero Coupon, 8/15/28, MBIA  No Opt. Call    4,306,841   
AAA    5,510    Cnty. of Harris, Hwy. Tolls RB, 5.00%, 8/15/30, FSA  08/12 @ 100    5,814,317   
AAA    10,030    Coppell Indpt. Sch. Dist. GO, Zero Coupon, 8/15/30, PSF  No Opt. Call    3,607,490   

2


BlackRock Insured Municipal Income Trust (BYM) (continued)         
(Percentage of Net Assets)         
 
 
 
    Principal             
   
Amount 
   
Option Call 
     
Rating1 
 
(000) 
  Description  Provisions2   
Value 
 
        Texas—(cont'd)         
AAA    $      2,350    Dallas Area Rapid Trans., Sales Tax RB, 5.00%, 12/01/31, AMBAC 
12/11 @ 100  
$
2,452,343   
        Harris Cnty.-Houston Sports Auth.,         
AAA    5,785       Hotel Occupancy Tax RB, Ser. H, Zero Coupon, 11/15/38, MBIA  11/31 @ 64.91    1,210,396   
AAA    6,160       Hotel Occupancy Tax RB, Ser. H, Zero Coupon, 11/15/39, MBIA  11/31 @ 60.976    1,208,099   
AAA    26,890       Lease RB, Ser. A-3, Zero Coupon, 11/15/38, MBIA  11/24 @ 43.826    5,253,230   
AAA    27,675       Lease RB, Ser. A-3, Zero Coupon, 11/15/39, MBIA  11/24 @ 41.258    5,081,960   
AAA    6,000    Lower Colorado River Auth., Misc. RB, 4.75%, 5/15/36, AMBAC  05/11 @ 100    6,123,000   
AAA    1,045    Montgomery Cnty. Mun. Util. Dist. No. 46, Pub. Impvts. Ad Valorem Ppty. Tax GO,         
           4.75%, 3/01/30, MBIA  03/14 @ 100    1,077,259   
AAA    9,500    Northside Indpt. Sch. Dist., Sch. Impvts. Ad Valorem Ppty. Tax GO, 5.125%, 6/15/29, PSF  06/14 @ 100    10,191,600   
AAA    3,000    Pearland, Ad Valorem Ppty. Tax GO, 4.75%, 3/01/29, FGIC  03/16 @ 100    3,129,930   
AAA    30,145    Tpke. Auth., Hwy. Impvt. Tolls RB, Ser. A, 5.00%, 8/15/42, AMBAC  08/12 @ 100    31,715,253   
BBB+    3,000    Tyler Cnty. Hlth. Facs. Dev. Corp., Hlth., Hosp. & Nursing Home Impvts. RB, Mother         
           Frances Hosp. Proj., 6.00%, 7/01/31  07/12 @ 100    3,235,320   
              108,490,349   
        Virginia—1.8%         
        Chesterfield Cnty. Indl. Dev. Auth., Ind. RB, Virginia Elec. & Pwr. Co. Proj.,         
Baa1    3,000       Ser. A, 5.875%, 6/01/17  11/10 @ 102    3,249,780   
Baa1    4,000       Ser. B, 5.875%, 6/01/17  11/10 @ 102    4,354,480   
              7,604,260   
        Washington—10.7%         
AAA    9,610    Central Washington Univ., Coll & Univ. RB, 5.00%, 5/01/34, FGIC  05/14 @ 100    10,202,360   
AAA    3,655    Chelan Cnty. Pub. Util. Dist. 1, Elec., Pwr. & Lt. RB, Chelan Hydro Sys. Proj., Ser. C,         
           5.125%, 7/01/33, AMBAC  07/12 @ 100    3,851,968   
AAA    9,500    City of Seattle, Parking Facilities Impvts. Ad Valorem Ppty. Tax GO, Ser. F, 5.125%,         
           12/15/28, MBIA  12/08 @ 100    9,739,210   
AAA    2,200    Cnty. of King, Swr. RB, 5.00%, 1/01/36, FSA  01/16 @ 100    2,359,214   
        Hlth. Care Facs. Auth., Hlth., Hosp. & Nursing Home RB, Providence Hlth. Sys. Proj.,         
AAA    3,000       4.50%, 10/01/35, FGIC  10/16 @ 100    3,025,980   
AAA    4,110       Ser. A, 4.625%, 10/01/34, FGIC  10/16 @ 100    4,187,227   
AAA    4,500    Port of Seattle, Port, Arpt. & Marina RB, Ser. A, 5.00%, 4/01/31, FGIC  10/11 @ 100    4,701,870   
AAA    6,380    Washington, Pub. Impvts. GO, Ser. A, 5.00%, 7/01/25, FSA  07/11 @ 100    6,682,795   
              44,750,624   
        West Virginia—0.3%         
AAA    1,295    Econ. Dev. Auth., Correctional Fac. Impvts. Lease RB, Correctional Juvenile Safety Proj.,         
           Ser. A, 5.00%, 6/01/29, MBIA  06/14 @ 100    1,376,494   
        Total Long-Term Investments (cost $574,559,464)      622,860,991   
        SHORT-TERM INVESTMENTS—4.6%         
        Ohio—1.7%         
VMIG1    7,0004   Hamilton Cnty. Hosp. Facs., Hlth., Hosp. & Nursing Home RB, Ser. A, 3.42%, 12/06/06,         
           FRWD  N/A    7,000,000   
        Nebraska—1.1%         
A-1+    4,8004   American Pub. Energy Agcy., Natural Gas RB, 3.49%, 12/07/06, FRWD  N/A    4,800,000   
   
Shares 
           
   
(000) 
           
        Money Market Fund—1.8%         
NR    7,400    AIM Tax Free Cash Reserve Portfolio - Institutional Class, 3.39%, 12/01/06  N/A    7,400,000   
        Total Short-Term Investments (cost $19,200,000)      19,200,000   
        Total Investments —153.9% (cost $593,759,4645)   
$
642,060,991   
        Other assets in excess of liabilities—1.0%      4,374,420   
        Preferred shares at redemption value, including dividends payable—(54.9)%      (229,075,765)  
        Net Assets Applicable to Common Shareholders—100%   
$
417,359,646   

__________
1     Using the highest of Standard & Poor's, Moody's Investors Service or Fitch's Ratings.
 
2     Date (month/year) and price of the earliest optional call or redemption. There may be other call provisions at varying prices at later dates.
 
3     This bond is prerefunded. U.S. government securities, held in escrow, are used to pay interest on this security, as well as retire the bond in full at the date indicated, typically at a premium to par.
 

3


BlackRock Insured Municipal Income Trust (BYM) (continued)
(Percentage of Net Assets)

 

4     For purposes of amortized cost valuation, the maturity date of this instrument is considered to be the earlier of the next date on which the security can be redeemed at par, or the next date on which the rate of interest is adjusted. Rate shown is rate as of November 30, 2006.
 
5     Cost for federal income tax purposes is $593,734,110. The net unrealized appreciation on a tax basis is $48,326,881, consisting of $48,326,881 gross unrealized appreciation and $0 gross unrealized depreciation.
 
  The value (market value plus accrued interest) of securities that are covered by insurance, which ensures the payment of principal and interest, represent approximately 86.4% of the Trust's managed assets.
   
AMBAC       
21.8% 
FGIC       
20.5% 
FSA       
16.2% 
MBIA       
22.0% 
PSF       
2.2% 
XLCA       
2.5% 
Other       
1.2% 

 
 
KEY TO ABBREVIATIONS 
 
AMBAC 
 
American Municipal Bond Assurance Corp.  PCRB 
 
Pollution Control Revenue Bond 
FGIC 
 
Financial Guaranty Insurance Co.  PSF 
 
Public School Fund Guaranteed 
FRWD 
 
Floating Rate Weekly Demand  RB 
 
Revenue Bond 
FSA 
 
Financial Security Assurance  ST 
 
Special Tax 
GO 
 
General Obligation  XLCA 
 
XL Capital Assurance 
MBIA 
 
Municipal Bond Insurance Assoc.       
 

 

4


Item 2. Controls and Procedures.

(a) The Registrant’s principal executive and principal financial officers have evaluated the Registrant’s disclosure controls and procedures within 90 days of this filing and have concluded, as of that date, that the Registrant’s disclosure controls and procedures were reasonably designed to ensure that information required to be disclosed by the Registrant in this Form N-Q was recorded, processed, summarized, and reported within the required time periods and that information to be disclosed by the Registrant in this Form N-Q was accumulated and communicated to the Registrant’s management, including its principal executive and principal financial officers, as appropriate, to allow timely decisions regarding required disclosure.

(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 (17 CFR 270.30a -3(d)) 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.

Separate certifications of the Registrant’s Principal Executive and Financial Officers pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 are attached as EX-99.CERT.


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)      BlackRock Insured Municipal Income Trust           
 
By:      /s/ Donald C. Burke                         
Name: Donald C. Burke 
Title: Treasurer and Principal Financial Officer 
Date: January 25, 2007 

      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/ Robert S. Kapito                         
Name: Robert S. Kapito 
Title: President and Principal Executive Officer 
Date: January 25, 2007 
 
By:        /s/ Donald C. Burke                         
Name: Donald C. Burke 
Title: Treasurer and Principal Financial Officer 
Date: January 25, 2007