Exhibit 99.1

(MERCK LOGO)                                                        NEWS RELEASE

Media Contact:    Amy Rose             Investor Contact: Graeme Bell
                  (908) 423-6537                         (908) 423-5185

   MERCK ANNOUNCES STRONG FULL-YEAR AND FOURTH-QUARTER 2005 EARNINGS; RESERVES
            AN ADDITIONAL $295 MILLION FOR VIOXX LEGAL DEFENSE COSTS

- -     Full-Year 2005 Earnings Per Share (EPS) Were $2.53, Including the Impact
      of Reserving an Additional $295 Million for VIOXX Legal Defense Costs and
      Excluding 31 Cents Related to Net Tax Charge and 12 Cents Related to
      Restructuring Charge; Full-Year Reported EPS Were $2.10

- -     Double-Digit Annual Sales Growth of SINGULAIR and Strong Uptake of VYTORIN
      Drove Full-Year 2005 Results

- -     EPS for the Fourth Quarter Were 64 Cents, Including the Addition to the
      VIOXX Legal Defense Reserve and Excluding a Charge of 12 Cents Related to
      Restructuring and an Approximately 1 Cent Tax Charge Related to Earnings
      Repatriation; Reported EPS Were 51 Cents

- -     Company's Global Restructuring Program Announced in November Remains on
      Track; Approximately 1,100 Positions Were Eliminated by Year End

- -     Merck Reaffirms Full-Year 2006 EPS Range of $2.28 to $2.36, Excluding
      Restructuring Charges; Reported 2006 EPS Range of $1.98 to $2.12
      Reaffirmed

- -     Company Continues to Expect Revenue Growth, Including Revenue from Joint
      Ventures, and Double-Digit Compound Annual Operating Earnings Growth Over
      the Next Three to Five Years

WHITEHOUSE STATION, N.J., Jan. 31, 2006 - Merck & Co., Inc. today announced
strong full-year and fourth-quarter 2005 earnings results that included the
impact of reserving an additional $295 million in the fourth quarter for VIOXX
legal defense costs. Double-digit annual sales growth of SINGULAIR and strong
uptake of VYTORIN contributed significantly to earnings per share (EPS) for
2005, which were $2.53, including the addition to the VIOXX reserve and
excluding the impact of a net tax charge and the restructuring charges related
to the headcount reductions and site closures announced in November. Including
the impact of the restructuring charges and the net tax charge, reported EPS for
2005 were $2.10, compared to $2.61 for 2004.

      Net income was $4,631.3 million, compared to $5,813.4 million last year.
Worldwide sales were $22.0 billion for the year, compared to $22.9 billion for
2004. Total sales decreased 4% for the year, which reflects a decrease of 7%
related to the VIOXX withdrawal in 2004, offset by revenue growth in all other
products of 3%.

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      For the fourth quarter of 2005, EPS were $0.64 including the addition to
the VIOXX reserve and excluding $0.12 related to the charge for the global
restructuring program and an approximately $0.01 tax charge related to
repatriation of foreign earnings under the American Jobs Creation Act (AJCA).
Including the impact of the restructuring charge and the tax charge, reported
EPS for the fourth quarter were $0.51, compared to $0.50 for the fourth quarter
of 2004. Net income was $1,119.7 million and worldwide sales were $5.8 billion
for the fourth quarter of 2005. Global sales performance includes a 1%
unfavorable effect from foreign exchange for the quarter and a 1% favorable
effect for the year.

      "Merck's performance for the quarter and the full year was strong and
serves as a platform for the future," said Richard T. Clark, Chief Executive
Officer and President. "In December, we outlined our strategic plan to return
Merck to an industry-leading position and we've now begun the important work of
executing against it. We are focused on priority disease areas, redefining our
drug discovery and development model, working to achieve leadership in emerging
pharmaceutical markets, building a new commercial model and creating a lean and
flexible cost structure. I am confident in our ability to make this plan a
reality.

      "As a result, we continue to believe we can generate compound annualized
revenue growth, including 50% of the revenues from the joint ventures from which
the Company derives equity income, of between 4 to 6% through 2010. We also
believe we can deliver double-digit compound earnings growth, excluding
restructuring charges, over the next three to five years. The Company also
anticipates returning to bottom-line EPS growth, excluding restructuring
charges, beginning in 2007," Clark continued.

      As part of a global restructuring program announced in November, Merck
plans to sell or close five manufacturing sites and two preclinical sites by the
end of 2008. The manufacturing facilities included in that action are: Ponders
End, United Kingdom; Okazaki, Japan; Kirkland, Canada; Albany, Ga. and Danville,
Pa. in the United States. The two preclinical sites are in Okazaki and Menuma,
Japan. As a result, the Company recorded a $401 million restructuring charge in
the fourth quarter, representing $205 million of separation costs and $196
million of accelerated depreciation and asset impairment costs. The Company also
announced plans to close its basic research center in Terlings Park, United
Kingdom. As previously announced, Merck plans to eliminate approximately 7,000
positions as part of the global restructuring program. As of Dec. 31,
approximately 1,100 positions throughout the Company had been eliminated.

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      Materials and production costs increased 15% for the fourth quarter and 4%
for full year 2005. This includes $177 million recorded in the fourth quarter
primarily related to accelerated depreciation and asset impairment costs
associated with the global restructuring program. Excluding these costs,
materials and production increased 1% for the quarter and were comparable to the
full year 2004.

      Marketing and administrative expenses decreased 9% in the fourth quarter
of 2005 and 1% for the full year. Included in marketing and administrative
expenses are reserves solely for future legal defense costs for VIOXX litigation
recorded in the fourth quarter of 2005 and 2004 of $295 million and $604
million, respectively, as well as $141 million in costs associated with the
voluntary withdrawal of VIOXX recorded in 2004. Excluding these costs, marketing
and administrative expenses increased 6% for the quarter and for the full year.
The increase reflects activities required to prepare for the launch of three new
investigational vaccines and to maintain activities in support of Merck's
in-line products.

      Research and development expenses were $1.1 billion for the quarter,
comparable to the fourth quarter of 2004, and $3.8 billion for full year 2005,
representing a decrease of 4%. Included in 2005 are accelerated depreciation
costs of $19 million associated with the global restructuring program and
accelerated depreciation costs of $51 million and $103 million for the quarter
and full year, respectively, related to the closure of the basic research center
located in Terlings Park, United Kingdom. Included in 2004 are acquired research
expense of $178 million and licensing expense of $225 million representing the
initial payments for certain disclosed research collaborations.

      Restructuring costs were $229 million and $322 million for the quarter and
full year 2005 as compared to $19 million and $108 million for the quarter and
full year 2004. Included are $205 million in separation costs associated with
the global restructuring program recorded in the fourth quarter of 2005, as well
as $24 million and $117 million in separation costs from earlier restructuring
programs for the fourth quarter and full year 2005, respectively.

FIRST-QUARTER AND FULL-YEAR 2006 EPS GUIDANCE

      Merck anticipates first-quarter EPS of $0.62 to $0.66, excluding
restructuring charges, and anticipates reported first-quarter EPS of $0.52 to
$0.58. Merck reaffirms full-year 2006 EPS range of $2.28 to $2.36, excluding the
restructuring charges related to site closures and position

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eliminations. Merck reaffirms reported full-year 2006 EPS range of $1.98 to
$2.12. Please see pages 13-14 of this news release for details of Merck's
full-year 2006 financial guidance.

MERCK'S KEY FRANCHISES

      Merck's major franchises continue to rank either first or second in their
classes, in terms of worldwide sales, and to benefit from new indications, as
well as clinical results that support their safety and efficacy profiles.

      Worldwide sales of SINGULAIR, a once-a-day oral medicine indicated for the
treatment of chronic asthma and the relief of symptoms of allergic rhinitis,
were strong, reaching $819 million for the fourth quarter, representing growth
of 12% over fourth quarter 2004. Sales for the year were $3.0 billion, a 13%
increase over full year 2004.

      The continued demand for asthma medications and the new indication for
perennial allergic rhinitis drove double-digit growth for SINGULAIR in 2005. In
December, Merck announced a U.S. label change for SINGULAIR incorporating the
positive results from a clinical study that showed children with asthma taking
SINGULAIR had similar growth rates as children taking placebo. In the same
study, children taking an inhaled steroid had slower growth rates than children
on either SINGULAIR or placebo.

      Global sales of Merck's antihypertensive medicines, COZAAR AND HYZAAR**,
were $782 million for the fourth quarter, representing growth of 2% over fourth
quarter 2004. Sales for the year were $3.0 billion, an 8% increase over full
year 2004.

      COZAAR and HYZAAR belong to the AIIA class, which remains the fastest
growing class in the antihypertensive market. COZAAR/HYZAAR remained the number
one branded AIIA in Europe and number two branded AIIA in the United States in
2005. In October, the U.S. Food and Drug Administration (FDA) approved a new
tablet, HYZAAR 100-12.5 mg, a new dosage offering the once-daily efficacy of
COZAAR 100 mg with a low-dose diuretic.

      FOSAMAX and FOSAMAX PLUS D (launching under the name FOSAVANCE throughout
the European Union) together remain the most-prescribed medicine worldwide for
the treatment of postmenopausal, male and glucocorticoid-induced osteoporosis.
Global sales for the franchise were $789 million for the fourth quarter,
representing a decrease of 5% compared to fourth quarter 2004. U.S. sales for
the quarter remained solid, growing at 9%. Total global sales for the year were
$3.2 billion, a 1% increase over full year

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**    COZAAR and HYZAAR are registered trademarks of E.I. DuPont de Nemours &
      Company, Wilmington, Del.


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2004. Sales outside of the United States were affected by the availability of
generic alendronate sodium products in some markets, including the United
Kingdom, Canada and Germany.

      ZOCOR, Merck's statin for modifying cholesterol, achieved worldwide sales
of $1.1 billion in the fourth quarter, representing a decrease of 18% over the
fourth quarter of 2004. Sales for the year were $4.4 billion, a 16% decrease
from the full year of 2004. Sales outside of the United States were affected by
the availability of generic simvastatin. Merck's U.S. marketing exclusivity for
ZOCOR expires in June 2006.

      Merck earns ongoing revenue based on sales of products that are associated
with alliances, the most significant of which is AstraZeneca LP. Revenue from
AstraZeneca LP recorded by Merck was $440 million in the fourth quarter and $1.7
billion for the year.

MERCK'S OTHER PROMOTED MEDICINES

      Sales of Merck's other promoted medicines and vaccines were $1.6 billion
for the fourth quarter, representing growth of 4% as compared with the fourth
quarter of 2004. Sales for 2005 were $6.0 billion, a 9% increase over the
full-year 2004 period. These products treat or prevent a broad range of medical
conditions, including infectious disease, glaucoma, benign prostate enlargement,
migraine, arthritis and pain.

      The FDA recently approved an expanded indication for EMEND for use with
other antiemetic medicines for the prevention of nausea and vomiting associated
with initial and repeat courses of moderately emetogenic chemotherapy.

      PROQUAD, Merck's combination vaccine to help protect children against
measles, mumps, rubella and chickenpox in a single injection that launched in
September, is now covered by 87% of managed care plans. In December, PROQUAD was
made available in the Centers for Disease Control and Prevention's (CDC) Vaccine
for Children (VFC) program. The VFC program provides the vaccine to children who
are Medicaid-eligible, uninsured, underinsured or Native American.

      Merck announced in November that the FDA has approved INVANZ, a once-daily
injectable antibiotic, for the treatment of moderate to severe complicated foot
infection due to indicated pathogens in diabetic patients without osteomyelitis.
The approval was based on the results of the SIDESTEP study, the largest
prospective, randomized and double-blind clinical trial ever conducted in
diabetic patients with moderate to severe complicated foot infection. Foot
infections commonly occur in patients with diabetes and are difficult to treat.

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      On Jan. 18, 2006, the Company sued Hi-Tech Pharmacal Co., Inc. of
Amityville, New York for patent infringement in response to Hi-Tech's
application to the FDA seeking approval of a generic version of Merck's
ophthalmic drugs TRUSOPT and COSOPT, which are used for treating elevated
intraocular pressure in people with ocular hypertension or glaucoma. In the
lawsuits, Merck sued to enforce a patent covering an active ingredient,
dorzolamide, which is present in both TRUSOPT and COSOPT. Merck has elected not
to enforce two U.S. patents listed with the FDA which cover the combination of
dorzolamide and timolol, the two active ingredients in COSOPT. This lawsuit will
automatically stay FDA approval of Hi-Tech's Abbreviated New Drug Applications
(ANDAs) for 30 months or until an adverse court decision, whichever may occur
earlier. The patent covering dorzolamide provides exclusivity for TRUSOPT and
COSOPT until October 2008 (including six months of pediatric exclusivity). After
such time, the Company expects sales of these products to decline.

MERCK/SCHERING-PLOUGH PARTNERSHIP

      As reported by the Merck/Schering-Plough partnership, global sales of
ZETIA and VYTORIN in the aggregate reached $746 million for the fourth quarter
and combined new prescriptions reached 14.3% of the U.S. lipid-lowering market,
according to the most recent monthly IMS Health data. Sales for the year were
$2.4 billion.

      Global sales by the Merck/Schering-Plough cholesterol partnership of
ZETIA, the cholesterol-absorption inhibitor also marketed as EZETROL outside the
United States, reached $391 million in the fourth quarter, an increase of 19%
compared with the fourth quarter of 2004. Sales for the year were $1.4 billion,
a 33% increase over 2004. In the fourth quarter, ZETIA new prescriptions reached
6.3% of the U.S. lipid-lowering market, according to the most recent monthly IMS
Health data.

      Global sales of VYTORIN, also developed and marketed by the
Merck/Schering-Plough partnership, reached $355 million in the fourth quarter.
VYTORIN, marketed outside the United States as INEGY, is the first single
cholesterol treatment to provide LDL cholesterol lowering through dual
inhibition of cholesterol production and absorption. Sales for the year were
$1.0 billion. In the fourth quarter, VYTORIN new prescriptions reached 7.9% of
the U.S. lipid-lowering market, according to the most recent monthly IMS Health
data.

      The Company records the income from its interest in the
Merck/Schering-Plough partnership in Equity income from affiliates.

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MERCK'S PIPELINE

      Significant milestones were reached in December for Merck's three
late-stage investigational vaccines, ZOSTAVAX, ROTATEQ and GARDASIL.

      On Dec. 15, the FDA Advisory Committee unanimously agreed that the
extensive data from clinical trials in more than 40,000 people support the
efficacy and safety of ZOSTAVAX, Merck's investigational vaccine for the
prevention of shingles in adults age 60 and older. Merck presented several
studies of the investigational vaccine, including the Phase III Shingles
Prevention Study (SPS) of 38,500 adults age 60 and over. Results from the SPS
were published in the June 2 issue of the New England Journal of Medicine.

      The Company submitted a Biologics License Application (BLA) to the FDA on
April 25 for ZOSTAVAX. The Advisory Committee's recommendation is not binding on
the FDA but will be considered by the FDA in its review of the BLA. In addition
to the U.S. regulatory application, Merck has filed regulatory applications for
ZOSTAVAX in several other world markets, including the European Union, Canada
and Australia. If approved, ZOSTAVAX will be the only vaccine available to
prevent shingles.

      On Dec. 14, the FDA Advisory Committee unanimously agreed that the data
from the Phase III clinical trials in more than 70,000 infants support the
efficacy and safety of ROTATEQ, the Company's investigational vaccine developed
to prevent rotavirus gastroenteritis. The committee's recommendation is not
binding on the FDA, but will be considered by the FDA in its review of the BLA
that Merck submitted for ROTATEQ on April 5. The Advisory Committee's
recommendation was based on data from Phase III clinical trials, including the
Rotavirus Efficacy and Safety Trial (REST), one of the largest pre-licensure
vaccine clinical trials ever conducted. Results from the study were published in
the Jan. 5, 2006 issue of the New England Journal of Medicine. If approved,
ROTATEQ will be the only vaccine available in the United States to prevent
rotavirus gastroenteritis.

      In REST, ROTATEQ prevented 98% of severe cases of rotavirus
gastroenteritis caused by serotypes targeted by the vaccine. In the study,
ROTATEQ was generally well-tolerated as compared to placebo. Merck's
investigational vaccine also reduced rotavirus-related hospitalizations and
emergency room visits by more than 90%. ROTATEQ targets the five strains of
rotavirus - G1, G2, G3, G4 and P1 - responsible for more than 90% of rotavirus
disease around the world.

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      One of the primary goals of REST was to evaluate the safety of ROTATEQ
with respect to intussusception among vaccine and placebo recipients. There was
not an increased risk of intussusception observed in patients taking ROTATEQ
relative to placebo.

      In addition to the United States, Merck has filed for licensure of ROTATEQ
in more than 50 other countries worldwide. Also in December, Merck announced
that it has partnered with PATH to initiate clinical trials of ROTATEQ in Africa
and Asia in 2006.

      Merck submitted a BLA for GARDASIL, Merck's investigational cervical
cancer vaccine, to the FDA in December. Also in the fourth quarter, license
applications for GARDASIL were submitted to additional regulatory agencies in
the European Union and Australia. Merck is seeking priority review designation
(the FDA's goal is to review and act on priority review BLAs within six months
of receipt) for GARDASIL in the United States and similar designations in other
countries. GARDASIL is designed to protect against four types of human
papillomavirus (HPV) - types 16 and 18, which account for an estimated 70% of
cervical cancer cases, and HPV types 6 and 11, which account for an estimated
90% of genital wart cases.

      At the Infectious Diseases Society of America (IDSA) meeting in October
and the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC)
meeting in December, Merck presented data from FUTURE I and FUTURE II, pivotal
Phase III studies for GARDASIL. In the primary analysis of FUTURE II, GARDASIL
prevented 100% of CIN (cervical intraepithelial neoplasia) 2/3 and AIS
(adenocarcinoma in situ) caused by HPV types 6, 11, 16 and 18. In the primary
analysis of FUTURE I, GARDASIL prevented 100% of CIN (all grades) and external
genital lesions caused by HPV types 6, 11, 16 and 18. The primary analyses
included females age 16-26 who were not infected with these HPV types at
enrollment and who remained free of infection throughout the completion of the
vaccination regimen. Study follow-up of the primary analysis for both studies
was approximately 17 to 20 months.

      Merck is on track for filing in 2006 the New Drug Application (NDA) for
JANUVIA, the proposed trademark for the compound known as MK-431, its potent and
highly selective DPP-4 inhibitor that potentially offers a novel approach to
treating type 2 diabetes by providing substantial glucose lowering and good
tolerability in a convenient once-daily dose.

      As announced in December, Merck also plans to file an NDA in 2007 for
MK-431A, a combination of JANUVIA and metformin for the treatment of type 2
diabetes.

      As also announced in December, Merck has, or is on track to have by the
first quarter 2006, promising drugs in Phase III development for diabetes,
insomnia, high cholesterol, heart disease, and HIV/AIDS. The Phase III
candidates include:

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- -     Gaboxadol, a unique mechanism from Merck's alliance with H. Lundbeck A/S
      that has the potential to provide benefits beyond existing therapies with
      respect to sleep quality and next-day effects. Merck anticipates filing an
      NDA with the FDA in the first quarter of 2007.

- -     MK-524A and MK-524B, which hold significant promise in further addressing
      the critical need for lipid/cholesterol management. MK-524A is a novel
      approach to lowering LDL, raising HDL-C and lowering triglycerides.
      MK-524B combines MK-524A with the proven benefits of simvastatin to
      potentially reduce the risk of coronary heart disease beyond what statins
      provide alone. Merck expects to file NDAs with the FDA for both compounds
      in 2007.

- -     MK-518, which is expected to be the first in a new class of
      antiretrovirals that is effective in inhibiting integrase, an enzyme
      necessary for the survival of HIV. Merck expects to file an NDA with the
      FDA in 2007. In November, Merck presented initial Phase II clinical trial
      results at the European AIDS Clinical Society meeting.

      Merck continues its strategy of establishing strong external alliances to
complement our substantial internal research capabilities, including research
collaborations, licensing pre-clinical and clinical compounds and technology
transfers to drive both near- and long-term growth. During 2005, Merck signed 44
such agreements.

VIOXX UPDATE

      This update supplements information previously provided by the Company.
Commencing with the Company's report on Form 10-Q for the first quarter of 2006,
the Company generally intends to provide updates on VIOXX litigation through its
periodic filings with the Securities and Exchange Commission (SEC).

      As previously disclosed, individual and putative class actions have been
filed against the Company in state and federal courts alleging personal injury
and/or economic loss with respect to the purchase or use of VIOXX. A number of
these actions are coordinated in separate proceedings in a multidistrict
litigation in the U.S. District Court for the Eastern District of Louisiana (the
"MDL"), New Jersey state court, California state court, Texas state court and
Philadelphia, Pennsylvania. As of Dec. 31, 2005, the Company has been served or
is aware that it has been named as a defendant in approximately 9,650 lawsuits,
which include

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approximately 19,100 plaintiff groups alleging personal injuries resulting from
the use of VIOXX, and in approximately 190 putative class actions alleging
personal injuries and/or economic loss (all of the actions discussed in this
paragraph are collectively referred to as the "VIOXX Product Liability
Lawsuits"). Of these lawsuits, approximately 4,350 representing approximately
12,075 plaintiff groups are or are slated to be in the federal MDL and
approximately 4,200 representing approximately 4,200 plaintiff groups are
included in a coordinated proceeding in New Jersey Superior Court before Judge
Carol E. Higbee. In addition, as of Dec. 31, 2005, approximately 3,800 claimants
had entered into Tolling Agreements with the Company, which halt the running of
applicable statutes of limitations for those claimants who seek to toll claims
alleging injuries resulting from a thrombotic cardiovascular event that results
in a myocardial infarction or ischemic stroke.

      The Company has received a Civil Investigative Demand from a group of the
Attorneys General of 31 states and the District of Columbia who are
investigating whether the Company violated state consumer protection laws when
marketing VIOXX. The Company is cooperating with the Attorneys General in
responding to the Civil Investigative Demand.

      As previously reported, the trial in Garza v. Merck is currently ongoing
in Texas state District Court in Starr County before a jury, with Judge Alex W.
Gabert presiding, and the re-trial of Plunkett v. Merck is scheduled to commence
on Feb. 6, 2006 in New Orleans, Louisiana. Additional product liability trials
have also been scheduled. The Company cannot predict the timing of any trials
with respect to the VIOXX Shareholder Lawsuits. The Company believes that it has
meritorious defenses to the VIOXX Lawsuits and will vigorously defend against
them. In view of the inherent difficulty of predicting the outcome of
litigation, particularly where there are many claimants and the claimants seek
indeterminate damages, the Company is unable to predict the outcome of these
matters, and at this time, cannot reasonably estimate the possible loss or range
of loss with respect to the VIOXX Lawsuits.

      Legal defense costs expected to be incurred in connection with a loss
contingency are accrued when probable and reasonably estimable. As of Dec. 31,
2004, the Company had established a reserve of $675 million solely for its
future legal defense costs related to the VIOXX Lawsuits and the VIOXX
Investigations. During 2005, the Company spent $285 million in the aggregate in
legal defense costs worldwide related to (i) the VIOXX Product Liability
Lawsuits, (ii) the VIOXX Shareholder Lawsuits, (iii) the VIOXX Foreign Lawsuits,
and (iv) the VIOXX Investigations (collectively, the "VIOXX Litigation"). In the
fourth quarter, the Company

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recorded a charge of $295 million to increase the reserve solely for its future
legal defense costs related to VIOXX to $685 million at Dec. 31, 2005. This
reserve is based on certain assumptions and is the best estimate of the amount
that the Company believes, at this time, it can reasonably estimate will be
spent through 2007. Some of the significant factors considered in the
establishment and ongoing review of the reserve for the VIOXX legal defense
costs were as follows: the actual costs incurred by the Company up to that time;
the development of the Company's legal defense strategy and structure in light
of the scope of the VIOXX Litigation; the number of cases being brought against
the Company; the costs and outcomes of completed trials and the anticipated
timing, progression, and related costs of pre-trial activities and trials in the
VIOXX Product Liability Lawsuits. Events such as scheduled trials that are
expected to occur throughout 2006 and into 2007, and the inherent inability to
predict the ultimate outcomes of such trials, limit the Company's ability to
reasonably estimate its legal costs beyond the end of 2007. The Company will
continue to monitor its legal defense costs and review the adequacy of the
associated reserves.

      The Company has not established any reserves for any potential liability
relating to the VIOXX Litigation. Unfavorable outcomes in the VIOXX Lawsuits or
resulting from the VIOXX Investigations could have a material adverse effect on
the Company's financial position, liquidity and results of operations.

EARNINGS CONFERENCE CALL

      Investors are invited to a live Web cast of Merck's fourth-quarter
earnings conference call today at 9 a.m. ET, by visiting the Newsroom section of
Merck's Web site (www.merck.com/newsroom/webcast). Institutional investors and
analysts can participate in the call by dialing (706) 758-9927. Journalists are
invited to listen by calling (706) 758-9928. A replay of the Web cast will be
available starting at 1 p.m. ET today through 5 p.m. ET on Feb. 7. To listen to
the replay, dial (706) 645-9291 or (800) 642-1687 and enter ID # 4068624.

ABOUT MERCK

      Merck & Co., Inc. is a global research-driven pharmaceutical company
dedicated to putting patients first. Established in 1891, Merck discovers,
develops, manufactures and markets vaccines and medicines to address unmet
medical needs. The Company devotes

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                                      -12-


extensive efforts to increase access to medicines through far-reaching programs
that not only donate Merck medicines but help deliver them to the people who
need them. Merck also publishes unbiased health information as a not-for-profit
service. For more information, visit www.merck.com.

FORWARD-LOOKING STATEMENT

      This press release, including the financial information that follows,
contains "forward-looking statements" as that term is defined in the Private
Securities Litigation Reform Act of 1995. These statements are based on
management's current expectations and involve risks and uncertainties, which may
cause results to differ materially from those set forth in the statements. The
forward-looking statements may include statements regarding product development,
product potential or financial performance. No forward-looking statement can be
guaranteed, and actual results may differ materially from those projected. Merck
undertakes no obligation to publicly update any forward-looking statement,
whether as a result of new information, future events, or otherwise.
Forward-looking statements in this press release should be evaluated together
with the many uncertainties that affect Merck's business, particularly those
mentioned in the cautionary statements in Item 1 of Merck's Form 10-K for the
year ended Dec. 31, 2004, and in its periodic reports on Form 10-Q and Form 8-K,
which the Company incorporates by reference.

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                                      -13-

                        MERCK FINANCIAL GUIDANCE FOR 2006

      Worldwide sales will be driven by the Company's major products, including
the impact of new studies and indications. Sales forecasts for those products
for 2006 are as follows:



                                       WORLDWIDE
PRODUCT                                         2006 SALES
- -------                                         ----------
                                             
SINGULAIR (Respiratory)                         $3.3 to $3.6 billion
COZAAR/HYZAAR (Hypertension)                    $2.9 to $3.2 billion
FOSAMAX (Osteoporosis)                          $2.8 to $3.1 billion
ZOCOR (Cholesterol modifying)                   $2.3 to $2.6 billion
Other reported products*                        $6.3 to $6.6 billion


*     Other reported products comprise: AGGRASTAT, ARCOXIA, CANCIDAS, COSOPT,
      CRIXIVAN, EMEND, INVANZ, MAXALT, PRIMAXIN, PROPECIA, PROSCAR, STOCRIN,
      TIMOPTIC/TIMOPTIC XE, TRUSOPT, Vaccines and VASOTEC/VASERETIC.

o     Under an agreement with AstraZeneca (AZN), Merck receives revenue at
      predetermined percentages of the U.S. sales of certain products by AZN,
      most notably NEXIUM. In 2006, Merck anticipates these revenues to be
      approximately $1.5 to $1.7 billion.

o     Equity income from affiliates includes the results of the Merck and
      Schering-Plough collaboration combined with the results of Merck's other
      joint venture relationships. Equity Income from Affiliates is expected to
      be approximately $2.0 to $2.3 billion for 2006.

o     Product gross margin percentage is estimated to be approximately 75 to 77%
      for the full-year 2006. This guidance excludes the portion of the
      restructuring costs (detailed below) that will be included in product
      costs and will affect reported PGM in 2006.

o     Research and development expense (which excludes joint ventures) is
      estimated to continue at the same level as the full-year 2005 expense.
      Research and development expense in 2006 does not include the impact of
      stock option expense (detailed below).

o     Marketing and administrative expense is anticipated to increase at a low
      single-digit percentage growth rate over the full-year 2005 level. The
      full-year 2005 level excludes the charge taken in the fourth quarter
      related solely to future legal defense costs of VIOXX litigation. The 2006
      amount also does not include the impact of stock option expense.

o     The impact of stock option expense is expected to be approximately $220
      million, or approximately $0.07 per share and is included in the full-year
      2006 EPS range.

o     As part of the Company's restructuring of its operations, additional costs
      related to site closings, position eliminations and related costs will be
      incurred in 2006. The aggregate 2006 pretax expense related to these
      activities is estimated to be $800 million to $1.0 billion.

                                    - more -

                                      -14-


o     The consolidated 2006 tax rate is estimated to be approximately 24 to 26%.
      This guidance does not reflect the tax rate impact of restructuring costs.
      The effective tax rate to be applied to the Company's restructuring costs
      is at a higher level than the underlying effective tax rate guidance.

o     In 2006, the Company anticipates generating approximately $5 billion in
      free operating cash flow, after capital expenditures but before dividends
      and share repurchases.

o     Merck plans to continue its share repurchase program in 2006. As of Dec.
      31, $7.5 billion remains under the current buyback authorizations approved
      by Merck's Board of Directors.


      Given these guidance elements, Merck anticipates first-quarter EPS of
$0.62 to $0.66, excluding restructuring charges and anticipates reported
first-quarter EPS of $0.52 to $0.58. Merck reaffirms full-year 2006 EPS range of
$2.28 to $2.36, excluding the restructuring charges related to site closures and
position eliminations. Merck reaffirms reported full-year 2006 EPS range of
$1.98 to $2.12.

      This guidance does not reflect the establishment of any reserves for any
potential liability relating to the VIOXX litigation.

                                      # # #


                                      -15-


The following table shows the financial results for Merck & Co., Inc. and
subsidiaries for the quarter ended December 31, 2005, compared with the
corresponding period of the prior year.



                                                     Merck & Co., Inc.
                                                   Consolidated Results
                                      (In Millions Except Earnings per Common Share)
                                                 Quarter Ended December 31
                                                        (Unaudited)
                                      ----------------------------------------------
                                                                              %
                                             2005             2004         Change
                                             ----             ----         ------
                                                                  
Sales                                    $   5,765.9      $   5,748.0        --%

Costs, Expenses and Other
    Materials and production (1)             1,478.8          1,283.6        15
    Marketing and administrative (2)         2,139.1          2,347.2        -9
    Research and development (3)             1,112.0          1,108.6        --
    Restructuring costs (4)                    228.9             18.6         *
    Equity income from affiliates             (586.6)          (285.9)        *
    Other (income) expense, net               (126.3)          (103.9)       22

Income Before Taxes                          1,520.0          1,379.8        10

Taxes on Income (5)                            400.3            278.7

Net Income                               $   1,119.7      $   1,101.1         2

Average Shares Outstanding
   Assuming Dilution                         2,188.7          2,217.5

Earnings per Common Share
   Assuming Dilution                           $0.51            $0.50         2


- ----------

* > 100%

(1) Includes restructuring costs of $177 million recorded in the fourth quarter
2005 related to accelerated depreciation and asset impairment costs associated
with Merck's global restructuring program announced in November 2005.

(2) Includes reserves solely for future legal defense costs for VIOXX litigation
of $295 million and $604 million recorded in the fourth quarter of 2005 and
2004, respectively.

(3) Includes restructuring costs of $19 million recorded in the fourth quarter
2005 related to accelerated depreciation costs associated with Merck's global
restructuring program announced in November 2005. Also included is accelerated
depreciation of $51 million associated with the closure of the basic research
facility in Terlings Park, United Kingdom.

(4) Includes restructuring costs of $205 million recorded in the fourth quarter
2005 related to separations associated with Merck's global restructuring program
announced in November 2005. Also included are costs associated with earlier
separation programs of $24 million and $19 million recorded in 2005 and 2004,
respectively.

(5) The effective tax rate was 26.3% and 20.2% for the fourth quarter of 2005
and 2004, respectively. A tax charge of $27 million related to additional
repatriation of foreign earnings under the American Jobs Creation Act (AJCA) was
recorded in the fourth quarter 2005.


                                      -16-


The following table shows the financial results for Merck & Co., Inc. and
subsidiaries for the twelve months ended December 31, 2005, compared with the
corresponding period of the prior year.



                                                                    Merck & Co., Inc.
                                                                  Consolidated Results
                                                      (In Millions Except Earnings per Common Share)
                                                             Twelve Months Ended December 31
                                                                       (Unaudited)
                                                      ----------------------------------------------
                                                                                                   %
                                                    2005                      2004               Change
                                                    ----                      ----               ------
                                                                                        
Sales                                          $   22,011.9              $   22,938.6              -4%

Costs, Expenses and Other
    Materials and production (1)                    5,149.6                   4,959.8               4
    Marketing and administrative (2)                7,155.5                   7,238.7              -1
    Research and development (3)                    3,848.0                   4,010.2              -4
    Restructuring costs (4)                           322.2                     107.6              *
    Equity income from affiliates (5)              (1,717.1)                 (1,008.2)              70
    Other (income) expense, net                      (110.2)                   (344.0)             -68

Income Before Taxes                                 7,363.9                   7,974.5              -8

Taxes on Income (6)                                 2,732.6                   2,161.1

Net Income                                     $    4,631.3              $    5,813.4              -20

Average Shares Outstanding
   Assuming Dilution                                2,200.4                   2,226.4

Earnings per Common Share
   Assuming Dilution                                   $2.10                     $2.61             -20


- ----------

* > 100%

(1) Includes restructuring costs of $177 million recorded in the fourth quarter
2005 related to accelerated depreciation and asset impairment costs associated
with Merck's global restructuring program announced in November 2005.

(2) Includes reserves solely for future legal defense costs for VIOXX litigation
of $295 million and $604 million recorded in the fourth quarter 2005 and 2004,
respectively, and $141 million in costs associated with the withdrawal of VIOXX
recorded in 2004.

(3) Includes restructuring costs of $19 million recorded in the fourth quarter
2005 related to accelerated depreciation associated with Merck's global
restructuring program announced in November 2005. Also included is accelerated
depreciation of $103 million recorded in 2005 associated with the closure of the
basic research facility in Terlings Park, United Kingdom. 2004 results include
acquired research expense of $178 million as well as $225 million representing
the initial payments for certain disclosed research collaborations.

(4) Includes restructuring costs of $205 million recorded in the fourth quarter
2005 related to separations associated with Merck's global restructuring program
announced in November 2005. Also included are costs associated with earlier
separation programs of $117 million and $108 million recorded in 2005 and 2004,
respectively.

(5) Includes the equity income from Merck's joint ventures and partnerships with
AstraZeneca LP $834 million, Merck/Schering-Plough partnership $570 million, and
all other ventures $313 million. Merck's 50% of the revenues from the
Merck/Schering-Plough, Merial, Sanofi-Pasteur MSD and Johnson & Johnson-Merck
joint ventures and partnerships totaled $2.8 billion in 2005 and
$2.1 billion in 2004.

(6) The effective tax rate was 37.1% and 27.1% for the full year 2005 and 2004,
respectively. 2005 includes a net tax charge of $667 million which reflects $767
million related to the repatriation of foreign earnings under the American Jobs
Creation Act (AJCA), partially offset by a $100 million benefit associated with
the decision to implement certain tax planning strategies. These net tax charges
resulted in an increase of 9.1 percentage points to the effective tax rate for
the full year of 2005.