ZOLINZA(TM), Merck's Investigational Medicine for Advanced Cutaneous T-Cell Lymphoma (CTCL), to Receive Priority Review from U.S. Food and Drug Administration

Merck & Co., Inc. announced today that the Food and DrugAdministration (FDA) has accepted the New Drug Application (NDA) forZOLINZA(TM) (vorinostat, also known as suberoylanilide hydroxamicacid, SAHA) for the treatment of advanced cutaneous T-cell-lymphoma(CTCL) and that this NDA has been granted priority review by the FDA.A priority review designation is intended for products that addressunmet medical needs. Under the Prescription Drug User Fee Act (PDUFA),for NDAs filed in 2006, the FDA's goal is to review and act on NDAsdesignated as priority review within six months of receipt. Merckexpects FDA action on the NDA by early October 2006.

If approved, ZOLINZA would potentially be the first in a new classof anti-cancer therapies called histone deacetylase (HDAC) inhibitors.Histone deacetylation is thought to be a mechanism for silencing sometumor suppressor genes and other genes responsible for cell cycleprogression, cell proliferation, programmed cell death (apoptosis),and differentiation (transformation of young cells into specializedcells).

"HDAC inhibitors like ZOLINZA are very exciting to the cancercommunity," said Stephen H. Friend, M.D., Ph.D., executive vicepresident, Oncology, Merck Research Laboratories. "ZOLINZA is one ofseveral investigational therapies that represent an important part ofthe growing Merck Oncology franchise."

About ZOLINZA

ZOLINZA, also known as vorinostat or suberoylanilide hydroxamicacid (SAHA), is Merck's investigational histone deacetylase (HDAC)inhibitor and part of a new class of anti-tumoragents underinvestigation for the treatment of solid tumors and cancers of theblood (lymphomas). Histone acetylation and deacetylation effect generegulation by changing the conformation of DNA in chromatin - thedense part of the cell that is comprised of DNA and other proteins,mainly histones. ZOLINZA was granted fast-track and orphan drugdesignation for CTCL by the FDA.

About CTCL

CTCL, a type of non-Hodgkin's lymphoma, is a slow-growing form ofcancer in which some of the body's white blood cells known asT-lymphocytes or T-cells become malignant. Normal T-cells function byregulating the body's immune system in its job of fighting infectionsand other foreign antigens. In CTCL, the malignant T-cells are drawnto the skin, where some are deposited. Patients usually develop CTCLafter age 50. CTCL affects 20,000 patients in the United States, withanother 1,500 new cases reported each year.

About Merck Oncology

Merck Oncology focuses on all aspects of cancer care --prevention, treatment, and supportive care. Through strong internalresearch capabilities, selective alliances and acquisitions, andenabling technologies such as the Molecular Profiling platform ofRosetta, Merck Oncology is looking to lead in the discovery,development and delivery of targeted anti-cancer therapies customizedfor patient subpopulations. Today, the Company's areas of researchinclude anti-cancer therapies that target HDAC, Notch, Aurora Kinases,IGFR, PSCA and KSP; preventive and treatment cancer vaccines; andsupportive care products. Merck Oncology conducts research at sites inBoston, Seattle, West Point, Japan and Italy.

About Merck

Merck & Co., Inc. is a global research-driven pharmaceuticalcompany dedicated to putting patients first. Established in 1891,Merck currently discovers, develops, manufactures and markets vaccinesand medicines to address unmet medical needs. The company devotesextensive efforts to increase access to medicines through far-reachingprograms that not only donate Merck medicines but help deliver them tothe people who need them. Merck also publishes unbiased healthinformation as a not-for-profit service. For more information, visitwww.merck.com.

Forward-Looking Statement

This press release contains "forward-looking statements" as thatterm is defined in the Private Securities Litigation Reform Act of1995. These statements are based on management's current expectationsand involve risks and uncertainties, which may cause results to differmaterially from those set forth in the statements. The forward-lookingstatements may include statements regarding product development,product potential or financial performance. No forward-lookingstatement can be guaranteed, and actual results may differ materiallyfrom those projected. Merck undertakes no obligation to publiclyupdate any forward-looking statement, whether as a result of newinformation, future events, or otherwise. Forward-looking statementsin this press release should be evaluated together with the manyuncertainties that affect Merck's business, particularly thosementioned in the cautionary statements in Item 1 of Merck's Form 10-Kfor the year ended Dec. 31, 2005, and in its periodic reports on Form10-Q and Form 8-K, which the company incorporates by reference.

ZOLINZA(TM) is a registered trademark of Merck & Co., Inc.