MuniYield Insured Investment (MFT) -- Converted by SEC Publisher, created by BCL Technologies Inc., for SEC Filing

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 811-07156

Name of Fund: BlackRock MuniYield Insured Investment Fund (MFT)

Fund Address: 100 Bellevue Parkway, Wilmington, DE 19809

Name and address of agent for service: Donald C. Burke, Chief Executive Officer, BlackRock MuniYield Insured
Investment Fund, 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: 07/31/2009

Date of reporting period: 08/01/2008 – 10/31/2008

Item 1 – Schedule of Investments

BlackRock MuniYield Insured Investment Fund             
Schedule of Investments October 31, 2008 (Unaudited)    (Percentages shown are based on Net Assets) 
 
             Par     
State    Municipal Bonds        (000)    Value 
 
 
 
 
Florida - 148.1%    Alachua County, Florida, School Board, COP, 5.25%, 7/01/29 (a)    $1,300    $ 1,185,275 
   
 
 
    Boynton Beach, Florida, Utility System Revenue Refunding Bonds,         
    6.25%, 11/01/20 (b)(c)        700    783,097 
   
 
 
 
    Brevard County, Florida, Health Facilities Authority, Healthcare Facilities         
    Revenue Bonds (Health First Inc. Project), 5%, 4/01/36        2,000    1,251,640 
   
 
 
 
    Broward County, Florida, Educational Facilities Authority Revenue Bonds (Nova         
    Southeastern University), 5%, 4/01/31 (d)        1,720    1,568,605 
   
 
 
 
    Broward County, Florida, HFA, S/F Mortgage Revenue Refunding Bonds, AMT,         
    Series E, 5.90%, 10/01/39 (e)(f)(g)        1,100    1,020,976 
   
 
 
 
    Broward County, Florida, School Board, COP, Series A, 5.25%, 7/01/33 (h)    2,000    1,819,940 
   
 
 
    Daytona Beach, Florida, Utility System Revenue Refunding Bonds,         
    Series B, 5%, 11/15/27 (c)(i)        1,000    873,010 
   
 
 
 
    Deltona, Florida, Transportation Capital Improvement Revenue Bonds, 5.125%,         
    10/01/26 (i)        1,000    917,010 
   
 
 
 
    Emerald Coast, Florida, Utilities Authority, System Revenue Bonds,         
    5.25%, 1/01/36 (c)(i)        1,000    845,900 
   
 
 
 
    Florida HFA, Housing Revenue Bonds (Brittany Rosemont Apartments), AMT,         
    Series C-1, 6.75%, 8/01/14 (a)        910    910,473 
   
 
 
 
    Florida Housing Finance Corporation, Homeowner Mortgage Revenue Bonds,         
    AMT, Series 11, 5.95%, 1/01/32 (h)        1,520    1,330,304 
   
 
 
 
    Florida Housing Finance Corporation, Homeowner Mortgage Revenue Refunding         
    Bonds, AMT, Series 4, 6.25%, 7/01/22 (h)        295    299,738 
   
 
 
 
    Florida State Board of Education, Lottery Revenue Bonds, Series A,         
    6%, 7/01/10 (c)(j)        6,190    6,619,648 
   
 
 
 
    Florida State Governmental Utility Authority, Utility Revenue Bonds (Lehigh         
    Utility System), 5.125%, 10/01/33 (a)        1,000    920,200 
   
 
 
 
    Florida State Turnpike Authority, Turnpike Revenue Bonds (Department of         
    Transportation), Series B, 5%, 7/01/30        1,860    1,709,861 
   
 
 
 
    Hillsborough County, Florida, Aviation Authority Revenue Bonds, AMT, Series A,         
    5.50%, 10/01/38 (d)        2,505    1,989,746 
   
 
 
 
    Hillsborough County, Florida, Aviation Authority, Revenue Refunding Bonds,         
    AMT, Series C, 5.75%, 10/01/26 (d)        1,000    875,260 
   
 
 
 
    Hillsborough County, Florida, HFA, S/F Mortgage Revenue Bonds, AMT, Series 1,         
    5.375%, 10/01/49 (e)(f)(g)        1,340    1,137,446 
   
 
 
 
    Hillsborough County, Florida, IDA, PCR, Refunding (Tampa Electric Company         
    Project), Series B, 5.15%, 9/01/25        500    495,125 
 
 
 
 
Portfolio Abbreviations             

To simplify the listings of portfolio holdings in the Schedule of Investments, the names and descriptions of many of the securities have been abbreviated according to the list below.

AMT    Alternative Minimum Tax (subject to)    IDA    Industrial Development Authority 
COP    Certificates of Participation    IDR    Industrial Development Revenue Bonds 
GO    General Obligation Bonds    PCR    Pollution Control Revenue Bonds 
HFA    Housing Finance Agency    S/F    Single-Family 

1

BlackRock MuniYield Insured Investment Fund             
Schedule of Investments October 31, 2008 (Unaudited)    (Percentages shown are based on Net Assets) 
 
             Par     
State    Municipal Bonds        (000)    Value 
 
 
 
 
    Hillsborough County, Florida, School Board, COP, 5.375%, 7/01/09 (i)(j)    $6,000    $ 6,147,840 
   
 
 
    Hillsborough County, Florida, School Board, COP, 5%, 7/01/29 (i)    1,000    928,150 
   
 
 
    Jacksonville, Florida, Economic Development Commission, Health Care         
    Facilities Revenue Bonds (Mayo Clinic-Jacksonville), Series A,         
    5.50%, 11/15/36 (i)        1,000    882,210 
   
 
 
 
    Jacksonville, Florida, Economic Development Commission, Health Care         
    Facilities Revenue Bonds (Mayo Clinic-Jacksonville), Series B,         
    5.50%, 11/15/36 (i)        750    661,657 
   
 
 
 
    Jacksonville, Florida, Economic Development Commission, IDR (Metropolitan         
    Parking Solutions Project), AMT, 5.50%, 10/01/30 (k)        1,140    851,272 
   
 
 
 
    Jacksonville, Florida, Guaranteed Entitlement Revenue Refunding and         
    Improvement Bonds, 5.25%, 10/01/32 (c)(i)        1,455    1,357,442 
   
 
 
 
    Jacksonville, Florida, HFA, Homeowner Mortgage Revenue Refunding Bonds,         
    AMT, Series A-1, 5.625%, 10/01/39 (e)(f)(g)        975    854,080 
   
 
 
 
    Jacksonville, Florida, Health Facilities Authority, Hospital Revenue Bonds         
    (Baptist Medical Center Project), 5%, 8/15/37 (h)        2,875    2,514,820 
   
 
 
 
    Jacksonville, Florida, Port Authority Revenue Bonds, AMT, 6%, 11/01/38 (d)    2,550    2,269,627 
   
 
 
    Jacksonville, Florida, Port Authority, Seaport Revenue Bonds, AMT,         
    5.625%, 11/01/26 (i)        1,225    1,054,113 
   
 
 
 
    Jacksonville, Florida, Sales Tax Revenue Bonds, 5%, 10/01/30    2,000    1,784,620 
   
 
 
    Lakeland, Florida, Electric and Water Revenue Refunding Bonds, Series A, 5%,         
    10/01/28 (i)        2,000    1,866,040 
   
 
 
 
    Lee County, Florida, Airport Revenue Bonds, AMT, Series A,         
    6%, 10/01/29 (h)        1,000    890,950 
   
 
 
 
    Lee County, Florida, Capital Revenue Bonds, 5.25%, 10/01/23 (a)    2,285    2,254,678 
   
 
 
    Lee Memorial Health System, Florida, Hospital Revenue Bonds, Series A, 5%,         
    4/01/32 (a)        2,000    1,756,900 
   
 
 
 
    Leesburg, Florida, Capital Improvement Revenue Bonds, 5.25%,         
    10/01/34 (c)(i)        1,000    882,880 
   
 
 
 
    Martin County, Florida, Utilities System Revenue Bonds, 5.125%,         
    10/01/33 (a)        1,000    877,030 
   
 
 
 
    Miami Beach, Florida, Water and Sewer Revenue Bonds, 5.75%, 9/01/25 (a)    2,000    2,010,720 
   
 
 
    Miami-Dade County, Florida, Aviation Revenue Bonds, AMT, Series A,         
    5%, 10/01/33 (h)        6,300    4,740,183 
   
 
 
 
    Miami-Dade County, Florida, Aviation Revenue Bonds (Miami International         
    Airport), AMT, Series A, 6%, 10/01/24 (c)(i)        5,000    4,511,000 
   
 
 
 
    Miami-Dade County, Florida, Aviation Revenue Refunding Bonds (Miami         
    International Airport), AMT, Series A, 5.25%, 10/01/41 (h)    1,200    899,460 
   
 
 
    Miami-Dade County, Florida, Aviation Revenue Refunding Bonds (Miami         
    International Airport), AMT, Series A, 5.50%, 10/01/41 (h)    2,400    1,881,000 
   
 
 

2

BlackRock MuniYield Insured Investment Fund             
Schedule of Investments October 31, 2008 (Unaudited)    (Percentages shown are based on Net Assets) 
 
             Par     
State    Municipal Bonds        (000)    Value 
 
 
 
 
    Miami-Dade County, Florida, Aviation Revenue Refunding Bonds (Miami         
    International Airport), AMT, Series B, 5%, 10/01/19 (d)(l)    $4,200    $ 3,697,050 
   
 
 
    Miami-Dade County, Florida, Expressway Authority, Toll System Revenue Bonds,     
    Series B, 5.25%, 7/01/27 (c)(i)        1,000    919,530 
   
 
 
 
    Miami-Dade County, Florida, Expressway Authority, Toll System Revenue Bonds,     
    Series B, 5%, 7/01/33 (c)(i)        2,400    2,057,160 
   
 
 
 
    Miami-Dade County, Florida, HFA, Home Ownership Mortgage Revenue Bonds,     
    AMT, Series A, 5.55%, 10/01/49 (e)(f)(g)        1,200    1,062,768 
   
 
 
 
    Miami-Dade County, Florida, IDA, IDR (BAC Funding Corporation Project),     
    Series A, 5.375%, 10/01/30 (a)        1,655    1,584,100 
   
 
 
 
    Miami-Dade County, Florida, School Board, COP, Refunding, Series B, 5.25%,     
    5/01/28 (d)        1,760    1,685,464 
   
 
 
 
    Miami-Dade County, Florida, School Board, COP, Refunding, Series B, 5.25%,     
    5/01/30 (d)        1,415    1,343,373 
   
 
 
 
    Miami-Dade County, Florida, School Board, COP, Series A, 5.50%,         
    10/01/09 (h)(j)        2,000    2,069,360 
   
 
 
 
    Miami-Dade County, Florida, Solid Waste System Revenue Bonds, 5.25%,     
    10/01/30 (i)        1,865    1,689,261 
   
 
 
 
    Miami-Dade County, Florida, Special Obligation Revenue Bonds,         
    Sub-Series A, 5.186%, 10/01/31 (i)(m)        4,375    974,838 
   
 
 
 
    Miami-Dade County, Florida, Special Obligation Revenue Bonds,         
    Sub-Series A, 5.203%, 10/01/33 (i)(m)        5,735    1,116,605 
   
 
 
 
    Orange County, Florida, Educational Facilities Authority, Educational Facilities     
    Revenue Refunding Bonds (Rollins College Project),             
    5.50%, 12/01/32 (a)        4,765    4,503,783 
   
 
 
 
    Orange County, Florida, Health Facilities Authority, Hospital Revenue Bonds     
    (Orlando Regional Healthcare), 6%, 12/01/12 (j)        1,835    2,021,803 
   
 
 
 
    Orange County, Florida, Health Facilities Authority, Hospital Revenue         
    Refunding Bonds (Orlando Regional Healthcare), Series B,         
    5.25%, 12/01/29 (h)        1,450    1,375,557 
   
 
 
 
    Orange County, Florida, Sales Tax Revenue Refunding Bonds, Series A, 5.125%,     
    1/01/23 (c)(i)        1,000    960,500 
   
 
 
 
    Orange County, Florida, Tourist Development, Tax Revenue Refunding Bonds,     
    5%, 10/01/29 (a)        2,190    1,930,879 
   
 
 
 
    Orlando, Florida, Senior Tourist Development Tax Revenue Bonds (6th Cent     
    Contract Payments), Series A, 5.25%, 11/01/38 (d)        2,000    1,812,980 
   
 
 
 
    Orlando-Orange County Expressway Authority, Florida, Expressway Revenue     
    Bonds, Series B, 5%, 7/01/30 (a)        4,000    3,509,400 
   
 
 
 
    Orlando-Orange County Expressway Authority, Florida, Expressway Revenue     
    Bonds, Series B, 5%, 7/01/35 (a)        6,815    5,793,432 
   
 
 
 
    Osceola County, Florida, Tourist Development Tax Revenue Bonds, Series A,     
    5.50%, 10/01/27 (c)(i)        1,100    1,032,317 
   
 
 
 

3

BlackRock MuniYield Insured Investment Fund             
Schedule of Investments October 31, 2008 (Unaudited)    (Percentages shown are based on Net Assets) 
 
             Par     
State    Municipal Bonds        (000)    Value 
 
 
 
 
    Palm Beach County, Florida, Criminal Justice Facilities Revenue Bonds, 7.20%,         
    6/01/15 (c)(i)        $1,500    $ 1,739,310 
   
 
 
 
    Palm Beach County, Florida, School Board, COP, Refunding, Series D,         
    5.25%, 8/01/21 (h)        2,000    2,001,860 
   
 
 
 
    Palm Beach County, Florida, School Board, COP, Series A, 6%,         
    8/01/10 (c)(j)        5,000    5,349,300 
   
 
 
 
    Palm Beach County, Florida, School Board, COP, Series A, 5%, 8/01/31 (h)    1,300    1,164,878 
   
 
 
    Panama City, Florida, Water and Sewer Revenue Bonds, Series B,         
    5.25%, 10/01/22 (i)        1,500    1,494,075 
   
 
 
 
    Polk County, Florida, Utility System Revenue Bonds, 5.25%, 10/01/22 (c)(i)    1,000    976,810 
   
 
 
    Port St. Lucie, Florida, Utility Revenue Bonds, 5.25%, 9/01/24 (i)    1,055    995,329 
   
 
 
    Saint Johns County, Florida, Ponte Vedra Utility System Revenue Bonds,         
    5%, 10/01/31 (h)        2,425    2,160,918 
   
 
 
 
    Saint Johns County, Florida, Ponte Vedra Utility System Revenue Bonds,         
    5%, 10/01/35 (h)        1,000    875,650 
   
 
 
 
    Saint Johns County, Florida, Sales Tax Revenue Bonds, Series A,         
    5.25%, 10/01/31 (a)        1,400    1,286,376 
   
 
 
 
    Saint Lucie, Florida, West Services District, Utility Revenue Bonds,         
    5.25%, 10/01/34 (i)        1,000    859,860 
   
 
 
 
    Santa Rosa County, Florida, School Board, COP, Refunding, Series 2,         
    5.25%, 2/01/26 (c)(i)        2,000    1,852,120 
   
 
 
 
    South Lake County, Florida, Hospital District Revenue Bonds (South Lake         
    Hospital Inc.), 5.80%, 10/01/34        1,000    784,670 
   
 
 
 
    University of Central Florida Athletics Association Inc., COP, Series A, 5.25%,         
    10/01/34 (c)(i)        2,280    1,817,092 
   
 
 
 
    University of Central Florida, COP (UCF Convocation Center), Series A,         
    5%, 10/01/35 (c)(i)        2,820    2,279,321 
   
 
 
 
    Village Center Community Development District, Florida, Recreational Revenue         
    Bonds, Series A, 5.375%, 11/01/34 (i)        1,640    1,434,000 
   
 
 
 
    Village Center Community Development District, Florida, Recreational Revenue         
    Bonds, Series A, 5.125%, 11/01/36 (i)        1,000    832,670 
   
 
 
 
    Village Center Community Development District, Florida, Utility Revenue         
    Bonds, 5.25%, 10/01/23 (i)        2,585    2,509,440 
   
 
 
 
    Village Center Community Development District, Florida, Utility Revenue         
    Bonds, 5.125%, 10/01/28 (i)        3,030    2,675,975 
   
 
 
 
    Volusia County, Florida, IDA, Student Housing Revenue Bonds (Stetson         
    University Project), Series A, 5%, 6/01/25 (n)        1,000    825,170 
   
 
 
 
    Volusia County, Florida, IDA, Student Housing Revenue Bonds (Stetson         
    University Project), Series A, 5%, 6/01/35 (n)        1,000    743,810 
               
                144,228,720 

4

BlackRock MuniYield Insured Investment Fund             
Schedule of Investments October 31, 2008 (Unaudited)    (Percentages shown are based on Net Assets) 
 
                     Par     
State    Municipal Bonds        (000)    Value 
 
 
 
 
Nevada - 2.1%    Clark County, Nevada, Water Reclamation District, Limited Tax, GO,         
    6%, 7/01/38        $2,010    $ 2,046,682 
 
 
 
 
Puerto Rico - 0.8%    Puerto Rico Public Buildings Authority, Government Facilities Revenue         
    Refunding Bonds, Series I, 5%, 7/01/36 (o)        1,000    795,570 
 
 
 
 
Texas - 1.4%    North Texas Tollway Authority, System Revenue Refunding Bonds, First Tier,         
    Series K-1, 5.75%, 1/01/38 (d)        1,400    1,350,076 
 
 
 
 
    Total Municipal Bonds - 152.4%            148,421,048 
 
 
 
 
    Municipal Bonds Transferred to Tender Option Bond Trusts (p)         
 
 
 
Florida - 17.3%    Jacksonville Electric Authority, Florida, Saint John's River Power Park System         
    Revenue Bonds, Issue Three, Series 2, 5%, 10/01/37        1,290    1,133,007 
   
 
 
 
    Jacksonville, Florida, Sales Tax Revenue Bonds, 5%, 10/01/27 (i)    1,320    1,266,910 
   
 
 
    Lee County, Florida, HFA, S/F Mortgage Revenue Bonds (Multi-County Program),     
    AMT, Series A-2, 6%, 9/01/40 (e)(f)(g)        1,800    1,739,430 
   
 
 
 
    Manatee County, Florida, HFA, Homeowner Revenue Bonds, AMT, Series A, 5.9,     
    9/01/40 (e)(f)(g)        1,011    903,370 
   
 
 
 
    Miami-Dade County, Florida, Health Facilities Authority, Hospital Revenue         
    Refunding Bonds (Miami Children's Hospital), Series A, 5.625%, 8/15/18 (a)    6,960    7,482,974 
   
 
 
    South Broward, Florida, Hospital District, Hospital Revenue Bonds, 5.625%,         
    5/01/32 (i)        4,000    4,346,240 
 
 
 
 
    Total Municipal Bonds Transferred to Tender Option Bond Trusts - 17.3%        16,871,931 
 
 
 
    Total Long-Term Investments (Cost - $182,041,647) - 169.7%        165,292,979 
 
 
 
    Short-Term Securities        Shares     
 
 
 
 
    CMA Florida Municipal Money Fund, 1.20% (q)(r)        4,626,460    4,626,460 
 
 
 
 
    Total Short-Term Securities (Cost - $4,626,460) - 4.8%        4,626,460 
 
 
 
    Total Investments (Cost - $186,668,107*) - 174.5%            169,919,439 
    Liabilities in Excess of Other Assets - (1.7)%            (1,716,251) 
    Liability for Trust Certificates, Including Interest Expense         
    and Fees Payable - (8.8)%            (8,561,737) 
    Preferred Shares, at Redemption Value - (64.0)%            (62,283,708) 
           
 
    Net Assets Applicable to Common Shares - 100.0%        $ 97,357,743 
           

*      The cost and unrealized appreciation (depreciation) of investments as of October 31, 2008, as computed for federal income tax purposes, were as follows:
 
Aggregate cost    $ 175,574,773 
Gross unrealized appreciation    $ 2,557,601 
Gross unrealized depreciation                             (16,703,567) 
Net unrealized depreciation    $ (14,145,966) 

5

BlackRock MuniYield Insured Investment Fund
Schedule of Investments October 31, 2008 (Unaudited)

(a) AMBAC Insured.

(b) Security is collateralized by Municipal or U.S. Treasury Obligations.

(c) FGIC Insured.

(d) Assured Guaranty Insured.

(e) FHLMC Collateralized.

(f) FNMA Collateralized.

(g) GNMA Collateralized.

(h) FSA Insured.

(i) MBIA Insured.

(j) U.S. government securities, held in escrow, are used to pay interest on this security as well as to
retire the bond in full at the date indicated, typically at a premium to par.

(k) ACA Insured.

(l) XL Capital Insured.

(m) Represents a zero-coupon bond. Rate shown reflects the effective yield at the time of purchase.

(n) CIFG Insured.

(o) Commonwealth Guaranteed.

(p) Securities represent bonds transferred to a tender option bond trust in exchange for which the Fund acquired
residual interest certificates. These securities serve as collateral in a financing transaction.

(q) Investments in companies considered to be an affiliate of the Fund, for purposes of Section 2(a)(3) of
the Investment Company Act of 1940, were as follows:

    Affiliate    Net Activity    Income 
   
 
 
    CMA Florida Municipal Money Fund    (7,785,584)    $24,954 
   
 
 
(r)    Represents the current yield as of report date.         

BlackRock MuniYield Insured Investment Fund

Schedule of Investments October 31, 2008 (Unaudited)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities. For information about the Fund's policy regarding valuation of investments and other significant accounting policies, please refer to the Fund's most recent financial statements as contained in its annual report.

The following table summarizes the inputs used as of October 31, 2008 in determining the fair valuation of the Fund's investments:

Valuation    Investments in 
Inputs    Securities 
Level 1    $ 4,626,460 
Level 2    165,292,979 
Level 3    - 
Total    $ 169,919,439 

7

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 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 MuniYield Insured Investment Fund

By: /s/ Donald C. Burke
Donald C. Burke
Chief Executive Officer of
BlackRock MuniYield Insured Investment Fund

Date: December 19, 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 MuniYield Insured Investment Fund

Date: December 19, 2008

By: /s/ Neal J. Andrews
Neal J. Andrews
Chief Financial Officer (principal financial officer) of
BlackRock MuniYield Insured Investment Fund

Date: December 19, 2008