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:     811-21702          

          BlackRock Health Sciences 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 Health Sciences 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:     October 31, 2006     
Date of reporting period:
     July 31, 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)
JULY 31, 2006

BlackRock Health Sciences Trust (BME)

Shares   Description   Value  

    LONG-TERM INVESTMENTS—96.5%    
    Common Stocks—96.5%    
    Biotechnology—15.5%    
246,300 1,2   Alexion Pharmaceuticals, Inc.   $    8,462,868  
37,800 1,2   Amgen, Inc.   2,636,172  
92,400 1   Applera Corp. - Celera Genomics Group   1,247,400  
54,000 1   Digene Corp.   2,279,340  
33,242 1   Exelixis, Inc.   295,854  
62,900 1   Genentech, Inc.   5,083,578  
67,700 1   ICOS Corp.   1,546,268  
39,167 1   InterMune, Inc.   625,497  
217,764 1   Keryx Biopharmaceuticals, Inc.   2,504,286  
83,200 1   Kosan Biosciences, Inc.   290,368  
51,589 1   Medimmune, Inc.   1,309,329  
72,000   Myogen, Inc.   2,221,920  
156,600 1   Regeneron Pharmaceuticals   2,139,156  
26,700 1   Vertex Pharmaceuticals, Inc.   894,984  

    Total Biotechnology   31,537,020  

    Electronics—2.8%    
141,900 1   Waters Corp.   5,772,492  

    Health Care—25.1%    
47,000   Alcon, Inc.   5,189,740  
20,200   Becton Dickinson & Co.   1,331,584  
98,000 1,2   Community Health Systems, Inc.   3,553,480  
33,800   Cooper Cos., Inc. (The)   1,493,960  
76,200 1   DaVita, Inc.   3,811,524  
119,600   Dentsply Intl., Inc.   3,743,480  
87,600   Edwards Lifesciences Corp.   3,875,424  
148,800   Manor Care, Inc.   7,447,440  
6,829   Mentor Corp.   303,617  
21,700 1   Northstar Neuroscience, Inc.   288,610  
82,600   Quest Diagnostics, Inc.   4,965,912  
146,200 1   Respironics, Inc.   5,201,796  
98,432 1   Varian Medical Systems, Inc.   4,460,938  
195,500 1   Wright Medical Group, Inc.   4,306,865  
18,500 1   Zimmer Holdings, Inc.   1,169,940  

    Total Health Care   51,144,310  

    Pharmaceuticals—51.1%    
106,500 2    Abbott Laboratories   5,087,505  
40,900   Allergan, Inc.   4,411,065  
56,000   AstraZeneca PLC   3,417,680  
337,238 1   BioMarin Pharmaceuticals, Inc.   4,927,047  
209,900   Bristol-Myers Squibb Co.   5,031,303  
295,100 1   Cardiome Pharma Corp.   3,597,269  
112,300 2    Caremark Rx, Inc.   5,929,440  
81,900 1   Cortex Pharmaceuticals, Inc.   221,130  
56,900 1   Cubist Pharmaceuticals, Inc.   1,304,148  
91,400 1   Gilead Sciences, Inc.   5,619,272  
92,000   GlaxoSmithKline PLC (ADR)   5,090,360  
83,600 1   Medco Health Solutions, Inc.   4,959,988  
266,600   Merck & Co., Inc.   10,735,982  
172,000   Novartis AG (ADR)   9,669,840  
178,400   Pfizer, Inc.   4,636,616  
85,000   Roche Holding AG   9,740,317  
482,000   Schering-Plough Corp.   9,852,080  
21,800   Shire PLC   1,057,518  
179,800   Wyeth   8,714,906  

    Total Pharmaceuticals   104,003,466  

    Retail—2.0%    
125,900   CVS Corp.   4,119,448  

    Total Common Stocks (cost $184,461,660)   196,576,736  

1


BlackRock Health Sciences Trust (BME) (continued)

Shares   Description   Value  

    SHORT-TERM INVESTMENTS—5.3%    
    Money Market Fund—3.0%    
6,137,631   Fidelity Institutional Money Market Prime Portfolio   $    6,137,631  

Principal        
Amount         
    U.S. Government and Agency Discount Notes—2.3%    
$4,800,000 3    Federal Home Loan Bank Disc. Notes, 4.95%, 8/1/06   4,800,000  

    Total Short-Term Investments (cost $10,937,631)   10,937,631  

Contracts          
    OUTSTANDING PUT OPTION PURCHASED—0.0%    
929   Waters Corp., strike price $40, expires 08/19/06 (cost $73,662)   55,740  

    Total investments before outstanding options written (cost $195,472,9534)   207,570,107  

    OUTSTANDING OPTIONS WRITTEN—(0.9)%    
    OUTSTANDING CALL OPTIONS WRITTEN—(0.9)%    
(100 ) Abbott Laboratories, strike price $45, expires 08/19/06   (30,000 )
(100 ) Abbott Laboratories, strike price $47.50, expires 11/18/06   (23,000 )
(561 ) Alexion Pharmaceuticals, Inc., strike price $35, expires 08/19/06   (56,100 )
(72 ) Alexion Pharmaceuticals, Inc., strike price $45, expires 11/18/06   (4,320 )
(10,000 ) Allergan, Inc., strike price $106, expires 09/15/06   (51,969 )
(50 ) Amgen, Inc., strike price $70, expires 08/19/06   (5,750 )
(150 ) Applera Corp. - Celera Genomics Group, strike price $15, expires 12/16/06   (11,250 )
(135 ) AstraZeneca PLC, strike price $65, expires 09/16/06   (8,775 )
(50 ) Becton Dickinson & Co., strike price $65, expires 08/19/06   (8,750 )
(250 ) BioMarin Pharmaceuticals, Inc., strike price $15, expires 09/16/06   (16,250 )
(250 ) BioMarin Pharmaceuticals, Inc., strike price $16, expires 11/10/06   (18,125 )
(30,000 ) Bristol-Myers Squibb Co., strike price $26, expires 09/15/06   (7,371 )
(20,000 ) Bristol-Myers Squibb Co., strike price $27.60, expires 11/17/06   (5,420 )
(750 ) Cardiome Pharma Corp., strike price $12.50, expires 09/16/06   (93,750 )
(20,000 ) Caremark Rx, Inc., strike price $52.50, expires 09/15/06   (50,680 )
(15,000 ) Community Health Systems, Inc., strike price $38, expires 09/15/06   (9,030 )
(20 ) Cooper Cos., Inc. (The), strike price $50, expires 11/18/06   (2,700 )
(300 ) CVS Corp., strike price $30, expires 08/19/06   (84,000 )
(12,000 ) CVS Corp., strike price $34, expires 11/10/06   (17,085 )
(120 ) DaVita, Inc., strike price $55, expires 09/16/06   (6,000 )
(30,000 ) Dentsply Intl., Inc., strike price $30.50, expires 09/15/06   (42,210 )
(10,000 ) Digene Corp., strike price $41, expires 09/15/06   (35,500 )
(100 ) Edwards Lifesciences Corp., strike price $45, expires 08/19/06   (6,250 )
(100 ) Edwards Lifesciences Corp., strike price $50, expires 11/18/06   (5,000 )
(100 ) Genentech, Inc., strike price $85, expires 09/16/06   (14,000 )
(170 ) Gilead Sciences, Inc., strike price $60, expires 08/19/06   (40,800 )
(50 ) Gilead Sciences, Inc., strike price $70, expires 11/18/06   (7,500 )
(200 ) GlaxoSmithKline PLC (ADR), strike price $55, expires 08/19/06   (18,000 )
(100 ) ICOS Corp., strike price $22.50, expires 08/19/06   (10,750 )
(100 ) InterMune, Inc., strike price $15, expires 08/19/06   (13,000 )
(101 ) Keryx Biopharmaceuticals, Inc., strike price $17.50, expires 09/16/06   (1,010 )
(250 ) Manor Care, Inc., strike price $45, expires 08/22/06   (132,500 )
(250 ) Manor Care, Inc., strike price $50, expires 11/18/06   (85,000 )
(130 ) Medco Health Solutions, Inc., strike price $55, expires 08/19/06   (62,400 )
(40,000 ) Merck & Co., Inc., strike price $35, expires 08/21/06   (215,231 )
(100 ) Merck & Co., Inc., strike price $37.50, expires 08/19/06   (30,000 )
(250 ) Merck & Co., Inc., strike price $39, expires 11/10/06   (73,750 )
(50 ) Myogen, Inc., strike price $30, expires 08/19/06   (10,750 )
(50 ) Myogen, Inc., strike price $30, expires 09/16/06   (14,250 )
(25,000 ) Novartis AG (ADR), strike price $56.50, expires 09/15/06   (39,412 )
(18,000 ) Pfizer, Inc., strike price $24, expires 09/28/06   (40,752 )
(90 ) Pfizer, Inc., strike price $25, expires 09/16/06   (12,150 )
(100 ) Quest Diagnostics, Inc., strike price $60, expires 08/19/06   (12,750 )
(100 ) Quest Diagnostics, Inc., strike price $65, expires 11/18/06   (13,750 )
(230 ) Regeneron Pharmaceuticals, strike price $12.50, expires 08/19/06   (35,075 )
(32,000 ) Respironics, Inc., strike price $36, expires 09/15/06   (40,941 )
(130 ) Roche Holding AG, strike price 230 CHF, expires 09/15/06   (22,925 )
(550 ) Schering-Plough Corp., strike price $20, expires 08/19/06   (35,750 )
(45,000 ) Schering-Plough Corp., strike price $21, expires 11/17/06   (38,240 )

2


BlackRock Health Sciences Trust (BME) (continued)

  Shares   Description   Value  

      OUTSTANDING CALL OPTIONS WRITTEN—(cont’d)    
  (100 ) Shire PLC, strike price $47.50, expires 10/21/06   $        (44,000 )
  (15,000 ) Varian Medical Systems, Inc., strike price $46.50, expires 09/15/06   (23,040 )
  (350 ) Waters Corp., strike price $45, expires 08/19/06   (1,750 )
  (100 ) Waters Corp., strike price $50, expires 11/18/06   (3,000 )
  (100 ) Wright Medical Group, Inc., strike price $22.50, expires 08/19/06   (5,750 )
  (100 ) Wright Medical Group, Inc., strike price $22.50, expires 09/16/06   (10,250 )
  (100 ) Wright Medical Group, Inc., strike price $25, expires 11/18/06   (8,500 )
  (675 ) Wyeth, strike price $47.50, expires 10/21/06   (189,000 )

      Total Outstanding Call Options Written (premium received ($1,246,309))   (1,905,261 )

      OUTSTANDING PUT OPTIONS WRITTEN—0.0%    
  (100 ) Allergan, Inc., strike price $100, expires 08/19/06   (5,500 )
  (220 ) Amylin Pharmaceuticals, Inc., strike price $40, expires 08/19/06   (4,400 )
  (210 ) Amylin Pharmaceuticals, Inc., strike price $45, expires 08/19/06   (16,275 )
  (150 ) AstraZeneca PLC, strike price $55, expires 08/19/06   (1,125 )
  (200 ) Caremark Rx, Inc., strike price $45, expires 08/19/06   (4,000 )
  (280 ) Vertex Pharmaceuticals, Inc., strike price $30, expires 08/19/06   (16,800 )
  (170 ) Vertex Pharmaceuticals, Inc., strike price $33.50, expires 08/23/06   (31,620 )

      Total Outstanding Put Options Written (premium received ($126,268))   (79,720 )

      Total Outstanding Options Written (premium received ($1,372,577))   (1,984,981 )

      Total investments net of outstanding options written—100.9%   $205,585,126  
      Liabilities in excess of other assets—(0.9)%   (1,818,128 )

      Net Assets—100.0%   $203,766,998  


1   Non-income producing security.  
2   Security, or a portion thereof, pledged as collateral for outstanding options written.  
3   Rate shown is the yield to maturity as of July 31, 2006.  
4   Cost for Federal income tax purposes is $198,792,423. The net unrealized appreciation on a tax basis is $8,777,684, consisting of $12,492,701 gross unrealized appreciation and $3,715,017 gross unrealized depreciation.  
       
    A category may contain multiple industries as defined by the SEC’s Standard Industry Codes. 


KEY TO ABBREVIATIONS

ADR — American Depository Receipt
CHF — Swiss Franc                            


3


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 Health Sciences Trust               

By:     /s/ Henry Gabbay                                                  
Name: Henry Gabbay
Title: Treasurer and Principal Financial Officer
Date: September 27, 2006

     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: September 27, 2006

By:     /s/ Henry Gabbay                                                  
Name: Henry Gabbay
Title: Treasurer and Principal Financial Officer
Date: September 27, 2006