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:__811-21177______

_______BlackRock California 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 California 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, 2005

Date of reporting period:__May 31, 2005_________________________________

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
MAY 31, 2005 (Unaudited)
BlackRock California Insured Municipal Income Trust (BCK)
  Principal          
    Amount     Option Call    
Rating1   (000)   Description Provisions2   Value  
      LONG-TERM INVESTMENTS—150.4%      
AAA   $  6,500   Benicia Unified Sch. Dist., Ser. B, Zero Coupon, 8/01/23, MBIA No Opt. Call   $    2,766,140  
AAA   4,000   California St., 5.00%, 6/01/31, AMBAC 12/14 @ 100   4,245,200  
        Ceres Unified Sch. Dist., Ser. B, FGIC,      
AAA   3,055      Zero Coupon, 8/01/30 08/12 @ 34.887   748,322  
AAA   3,180      Zero Coupon, 8/01/31 08/12 @ 32.868   733,340  
AAA   3,300      Zero Coupon, 8/01/32 08/12 @ 30.966   716,991  
AAA   3,440      Zero Coupon, 8/01/33 08/12 @ 29.174   703,652  
AAA   3,575      Zero Coupon, 8/01/34 08/12 @ 27.782   696,374  
AAA   3,275      Zero Coupon, 8/01/35 08/12 @ 26.186   601,290  
A   6,500   Dept. of Wtr. Res., Pwr. Sply. Rev., Ser. A, 5.25%, 5/01/20 05/12 @ 101   7,080,775  
AAA   2,385   Edl. Facs. Auth., Scripps Coll. Proj., 5.00%, 8/01/31, MBIA 08/11 @ 100   2,499,361  
AAA   4,500 3 Infrastructure & Econ. Dev., Rand Corp. Proj., Ser. A, 5.25%, 4/01/42, AMBAC 04/12 @ 100   4,766,715  
A3   2,600   Kaweah Delta Hlth. Care Dist., 6.00%, 8/01/34 08/12 @ 102   2,843,932  
AAA   2,000   Long Beach Unified Sch. Dist., Ser. D, 5.00%, 8/01/31, FSA 08/10 @ 101   2,095,900  
        Los Angeles Dept. of Wtr. & Pwr., Wtr. Wks. Rev., Ser. A, FGIC,      
AAA   5,000      5.00%, 7/01/43 07/12 @ 100   5,202,200  
AAA   5,000      5.125%, 7/01/41 07/11 @ 100   5,221,100  
AAA   5,000   Los Angeles Unified Sch. Dist., Ser. E, 5.125%, 1/01/27, MBIA 07/12 @ 100   5,321,400  
        Los Angeles Wstwtr. Sys., Ser. A,      
AAA   5,000      5.00%, 6/01/27, MBIA 06/13 @ 100   5,304,100  
AAA   6,025      5.00%, 6/01/32, FGIC 06/12 @ 100   6,307,091  
AAA   5,000   No. California Pwr. Agcy., Pub. Pwr. Rev., Hydroelec. Proj. 1, Ser. A, 5.00%, 7/01/28, MBIA 07/08 @ 101   5,264,850  
AAA   2,500 4 No. Orange Cnty. Cmnty. Coll. Dist., Ser. A, 5.00%, 8/01/12, MBIA N/A   2,805,775  
AAA   5,000   Pub. Wks. Brd., Dept. of Gen. Svcs., Ser. A, 5.00%, 12/01/27, AMBAC 12/12 @ 100   5,238,500  
AAA   5,000   Riverside Unified Sch. Dist., Ser. A, 5.00%, 2/01/27, FGIC 02/12 @ 101   5,293,050  
AAA   4,390   Sacramento Cnty. San. Dist. Fin. Auth., Sacramento Regl. Cnty. San., Ser. A,      
           5.00%, 12/01/35, AMBAC 12/14 @ 100   4,669,731  
AAA   5,295   San Diego Cnty. Wtr. Auth., COP, Ser. A, 5.00%, 5/01/32, MBIA 05/12 @ 101   5,552,019  
AAA   4,805   San Diego Redev. Agcy., Centre City Proj., Ser. A, 5.00%, 9/01/28, MBIA 09/11 @ 101   5,061,827  
AAA   4,000   San Diego Univ. Fndtn. Aux. Org., Ser. A, 5.00%, 3/01/37, MBIA 03/12 @ 100   4,166,920  
AAA   20,000   San Joaquin Hills Transp. Corridor Agcy., Toll Road Rev., Ser. A, Zero Coupon, 1/15/31, MBIA No Opt. Call   5,560,400  
AAA   6,000   San Jose Fin. Auth., Civic Ctr. Proj., Ser. B, 5.00%, 6/01/37, AMBAC 06/12 @ 100   6,240,360  
AAA   11,125   Santa Rosa Wstwtr., Ser. B, Zero Coupon, 9/01/27, AMBAC No Opt. Call   3,781,721  
AAA   3,000   Tustin Unified Sch. Dist., Spec. Tax Rev., Cmnty. Facs. Dist. 97-1, Ser. A,      
           5.00%, 9/01/38, FSA 09/12 @ 100   3,123,660  
AAA   4,000   Westlands Wtr. Dist., COP, 5.00%, 9/01/34, MBIA 09/12 @ 101   4,198,040  
        Total Long-Term Investments (cost $112,435,692)     118,810,736  
        SHORT-TERM INVESTMENTS—6.4%      
        California—5.2%      
A-1+   4,100 5 Econ. Recovery, Ser. C-5, 2.86%, 6/01/05, FRDD N/A   4,100,000  

1
BlackRock California Insured Municipal Income Trust (BCK) (continued)

             
    Shares          
    (000)   Description     Value  
        Money Market Fund—1.2%      
    950   AIM Tax Free Investment Co. Cash Reserve Portfolio     $ 950,000  
        Total Short-Term Investments (cost $5,050,000)     5,050,000  
        Total Investments—156.8% (cost $117,485,6926)     $123,860,736  
        Other assets in excess of liabilities—2.1%     1,638,906  
        Preferred shares at redemption value, including dividends payable—(58.9)%     (46,502,548 )
        Net Assets Applicable to Common Shareholders—100%     $  78,997,094  

1 Using the higher of S&P's, Moody's or Fitch's rating.
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 Securities, or a portion thereof, pledged as collateral with a value of $847,416 on 359 short U.S. Treasury Note futures contracts expiring Sept. 2005. The value of such contracts on May 31, 2005 was $40,662,359, with an unrealized loss of $584,218.
4 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.
5 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 as of May 31, 2005.
6 Cost for Federal income purposes is $117,486,352. The net unrealized appreciation on a tax basis is $6,374,384 consisting of $6,374,384 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 88.0% of the Trust's managed assets. 

KEY TO ABBREVIATIONS
       
AMBAC — American Municipal Bond Assurance Corporation FRDD — Floating Rate Daily Demand
COP — Certificate of Participation FSA — Financial Security Assurance
FGIC — Financial Guaranty Insurance Company MBIA — Municipal Bond Insurance Association

2

Item 2. Controls and Procedures.

(a) The registrant's principal executive officer and principal financial officer have evaluated the registrant's disclosure controls and procedures within 90 days of this filing and have concluded that the registrant’s disclosure controls and procedures are effective, as of that date, in ensuring that information required to be disclosed by the registrant in this Form N-Q was recorded, processed, summarized, and reported timely.

(b) The registrant's principal executive officer and principal financial officer are aware of no changes 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.

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 California Insured Municipal Income Trust___

By: __/s/ Henry Gabbay_____________________________________________
Name: Henry Gabbay
Title: Treasurer
Date: July 22, 2005

      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: Principal Executive Officer
Date: July 22, 2005

By: __/s/ Henry Gabbay_____________________________________________
Name: Henry Gabbay
Title: Principal Financial Officer
Date: July 22, 2005