PRESS RELEASE                            LIFE SCIENCES RESEARCH, INC.
                                         (OTCBB: LSRI)

                                         PO Box 2360
                                         Mettlers Road
                                         East Millstone, NJ 08875-2360

                                         For Further Information:
                                         Richard Michaelson
                                         Phone:   US: (732) 649-9961
                                         e-mail: LifeSciencesResearch@LSRinc.net


August 5, 2004

                      LSR ANNOUNCES SECOND QUARTER RESULTS


East  Millstone,  New  Jersey,  August 5, 2004 - Life  Sciences  Research,  Inc.
(OTCBB:  LSRI) announced today that revenues for the quarter ended June 30, 2004
were $38.3 million, operating profit was $4.0 million, or 10.4% of revenues, and
EBITDA  excluding  foreign  exchange  remeasurement  gains  associated  with the
Company's Bonds was $6.3 million, or 16.4% of revenues. Each of these represents
an  improvement  on the  quarter  ended March 31, 2004 which in turn were at the
highest level for five years when announced.

Revenues  for the quarter  were 17.3% above the  revenues for the same period in
the  prior  year of  $32.7  million.  Excluding  the  effect  of  exchange  rate
movements,  the  increase  was 7.6%.  The  Company  reported  net income for the
quarter ended June 30, 2004 of $1.2 million,  compared with $1.9 million for the
quarter  ended June 30, 2003.  Net income per common share for the quarter ended
June 30, 2004 was $0.10 compared with $0.16 in the quarter ended June 30, 2003.

The net income in the three months ended June 30, 2004 included  Other  Expenses
of $0.6  million  reflecting  a non-cash  foreign  exchange  remeasurement  loss
pertaining to the Convertible  Capital Bonds. In the three months ended June 30,
2003,  Other  Income of $2.2  million  comprised  a  non-cash  foreign  exchange
remeasurement gain of $2.0 million pertaining to the Convertible  Capital Bonds,
and a $0.2 million gain on the repurchase of Capital Bonds.  Excluding these non
cash items,  net income for the current  quarter was $1.6 million,  or $0.13 per
common share,  compared to $0.3 million,  or $0.03 per common share in the prior
year,  and  Earnings  before  Interest,  Taxes,  Depreciation  and  Amortization
("EBITDA")  was  $6.3  million  for the  second  quarter  of  2004,  or 16.4% of
revenues,  compared with $3.8 million, or 11.7% of revenues, for the same period
in the prior year.

Net cash  generated by operating  activities  totaled $2.3 million in the second
quarter of 2004 (compared with $1.7 million in second quarter 2003), after using
$2.5 million in increased working capital ($0.8 million in 2003). Net days sales
outstanding  were 22 days at June 30,  2004,  compared  with 17 days at June 30,
2003. Capital expenditure totaled $2.3 million in the second quarter of 2004.

Revenues  for the six months  ended June 30,  2004 at $75.6  million  were 17.0%
above  revenues for the same period last year of $64.6  million.  Excluding  the
effect of exchange rate movements,  the increase was 6.2%.  Operating Income for
that period was $6.3 million,  or 8.4%, compared to $3.3 million, or 5.1% in the
prior year.  The Company  reported  net income for the six months ended June 30,
2004 of $2.6  million,  compared with $1.5 million in the same period last year.
Net  income per common  share for the six months  ended June 30,  2004 was $0.22
compared with $0.13 in the same period last year.

The net income in the six months  ended June 30, 2004  included  Other Income of
$0.7  million   reflecting  a  non-cash  foreign  exchange   remeasurement  gain
pertaining to the  Convertible  Capital Bonds.  In the six months ended June 30,
2003,  Other  Income of $1.7  million  comprised  a  non-cash  foreign  exchange
remeasurement gain of $1.1 million  pertaining to the Convertible  Capital Bonds
and $0.6 million gain on the repurchase of Capital Bonds. Excluding Other Income
net income for the first six months of 2004 was $2.1 million or $0.17 per common
share,  compared  with $0.3  million or $0.02 per common share in the prior year
and EBITDA was $10.9 million, or 14.5% of revenues,  compared with $7.6 million,
or 11.7% of revenues, in the same period of 2003.

Net cash  generated by operating  activities  in the first half of 2004 was $3.7
million  (2003 $1.4  million)  after  using $4.2  million in  increased  working
capital ($3.4 million in 2003).  Capital  expenditure  in the first half of 2004
totaled $4.6 million.

Cash on hand at June 30, 2004 was $15.1 million  ($17.3  million at December 31,
2003). Long-term debt was $87.6 million at June 30, 2004 the same as at December
31, 2003.

Andrew Baker, LSR's Chairman and CEO said,  "Exceeding 10% operating profit this
quarter is a  significant  milestone  for LSR,  helped not only by the  positive
industry trends,  but by the focus and commitment that management and staff have
shown to customer  service and expense  management.  As both the  political  and
business  climate has improved for LSR, we are excited about the prospects  both
for  continued  growth and the return over the coming  quarters and years to the
more robust  operating  margins  that our  company  and peers have  historically
enjoyed."

Brian Cass, LSR's President and Managing  Director said, "The second quarter saw
a substantial  growth in orders over the second  quarter of 2003 with the result
that orders for the first half of the year were at record  levels.  Overall they
were 28% up on last  year  with a strong  contribution  from the  pharmaceutical
industry  which was 41% ahead of last year.  This growth in orders has increased
backlog and is supporting the continued growth in revenues."

Mr.  Cass  added,  "When we  announced  our  results  for the first  quarter  we
indicated  that we  expected  to see the impact of the  restructuring  of our UK
facilities  being felt during the second  quarter.  That indeed proved to be the
case.  This action played a significant  role in allowing us to reduce our total
costs in the  second  quarter  by $0.6  million  while at the same time  growing
revenues by $1 million."

LSR will hold an investor  conference  call to discuss the quarter's  results on
Friday  morning,  August 6, 2004 at 9:00 Eastern time. That call can be listened
to by dialing (888)  730-9141  (within U.S.) or (517) 308-9012  (outside  U.S.);
pass code 58804. We suggest calling five minutes prior to the scheduled call.

Life  Sciences  Research,  Inc.  is  a  global  contract  research  organization
providing product development  services to the pharmaceutical,  agrochemical and
biotechnology  industries.  LSR brings  leading  technology  and  capability  to
support its clients in  non-clinical  safety  testing of new  compounds in early
stage development and assessment.  The purpose of this work is to identify risks
to humans, animals or the environment resulting from the use or manufacture of a
wide  range of  chemicals  which  are  essential  components  of LSR's  clients'
products.   The  Company's   services  are  designed  to  meet  the   regulatory
requirements of governments  around the world. LSR operates research  facilities
in the United States (the Princeton  Research Center, New Jersey) and the United
Kingdom (Huntingdon and Eye, England).

This announcement  contains statements that may be forward-looking as defined by
the USA's Private Securities Litigation Reform Act of 1995. These statements are
based  largely on LSR's  expectations  and are  subject to a number of risks and
uncertainties,  certain  of  which  are  beyond  LSR's  control,  as more  fully
described in the Company's  SEC filings,  including its Form 10-K for the fiscal
year ended  December  31,  2003,  as filed with the US  Securities  and Exchange
Commission.

                              - tables to follow -




                           Life Sciences Research Inc.
                             Statement of Operations

                                    Unaudited

                                                      Three months ended June 30          Six months ended
                                                                                              June 30

(Dollars in thousands, except per share data)            2004           2003            2004            2003
                                                                                           
Net revenues                                             $38,315         $32,663        $75,551         $64,564
Cost of revenues                                        (28,111)        (25,442)       (57,546)        (50,815)
                                                      -----------    ------------    -----------     -----------
Gross profit                                              10,204           7,221         18,005          13,749
Selling, general and administrative expenses             (6,201)         (5,395)       (11,686)        (10,316)
Other operating expenses                                       -           (132)              -           (132)
                                                      -----------    ------------    -----------     -----------
Operating income                                           4,003           1,694          6,319           3,301
Interest income                                               14              23             28              39
Interest expense                                         (1,593)         (1,444)        (3,169)         (3,152)
Other income/(expense)                                     (625)           2,179            730           1,729
                                                      -----------    ------------    -----------     -----------
Income before income taxes                                 1,799           2,452          3,908           1,917
Income tax expense                                         (597)           (592)        (1,313)           (415)
                                                      -----------    ------------    -----------     -----------
Net income                                                $1,202          $1,860         $2,595          $1,502
                                                      -----------    ------------    -----------     -----------
Income per common share
- - Basic                                                    $0.10           $0.16          $0.22           $0.13
- - Diluted                                                  $0.10           $0.15          $0.21           $0.12

Weighted average common shares outstanding
- - Basic     (000's)                                       12,050          11,932         12,045          11,932
- - Diluted  (000's)                                        12,346          12,244         12,554          12,332








                           Life Sciences Research Inc.
                                  Balance Sheet



(Dollars in thousands, except per share data)                              June 30,         December 31,
                                                                               2004                 2003
ASSETS                                                                    Unaudited              Audited
                                                                                          
Current assets:
Cash and cash equivalents                                                   $15,135              $17,271
Accounts receivable, net of allowance of $546 and $561 in
    2004 and 2003 respectively                                               23,360               17,515
Unbilled receivables                                                         13,485                8,246
Inventories                                                                   1,771                1,901
Prepaid expenses and other current assets                                     3,573                4,610
                                                                     ---------------      ---------------
Total current assets                                                         57,324               49,543

Property and equipment, net                                                 103,000              101,547
Goodwill                                                                        847                  832
Unamortized Capital Bonds issue costs                                           345                  429
Deferred income taxes                                                         3,521                3,922
                                                                     ---------------      ---------------
Total assets                                                               $165,037             $156,273
                                                                     ---------------      ---------------
                                                                     ---------------      ---------------

LIABILITIES AND SHAREHOLDERS' EQUITY/(DEFICIT)
Current liabilities:
Accounts payable                                                            $10,124              $12,508
Accrued payroll and other benefits                                            2,525                4,152
Accrued expenses and other liabilities                                       17,478               13,695
Short term debt                                                                 263                  338
Fees invoiced in advance                                                     28,638               22,761
                                                                     ---------------      ---------------
Total current liabilities                                                    59,028               53,454

Long-term debt                                                               87,649               87,560
Pension liabilities                                                          22,097               21,414
Deferred income taxes                                                         3,237                2,291
                                                                     ---------------      ---------------
Total liabilities                                                           172,011              164,719
                                                                     ---------------      ---------------

Commitments and contingencies

Shareholders' equity/(deficit)
Voting Common Stock, $0.01 par value.  Authorized 50,000,000
Issued and outstanding at June 30, 2004: 12,049,534 (December 31,
2003: 12,034,883)                                                               120                  120
Non-Voting Common Stock, $0.01 par value.  Authorized 5,000,000
Issued and outstanding: None                                                      -                    -
Preferred Stock, $0.01 par value.  Authorized 5,000,000
Issued and outstanding: None                                                      -                    -
Paid in capital                                                              75,123               75,101
Less: Promissory notes for the issuance of common stock                       (643)                (661)
Accumulated comprehensive loss                                             (24,136)             (22,973)
Accumulated deficit                                                        (57,438)             (60,033)
                                                                     ---------------      ---------------
Total shareholders' equity /(deficit)                                       (6,974)              (8,446)
                                                                     ---------------      ---------------

Total liabilities and shareholders' equity /(deficit)                      $165,037             $156,273
                                                                     ---------------      ---------------