This study is to evaluate the efficacy, safety and tolerability of vorinostat in patients with lower risk Myelodysplastic Syndrome (MDS).

Inclusion Criteria:

Patient is a male or female, at least 18 years of age with low or intermediate-1 risk Myelodysplastic Syndrome (MDS) defined by the International Prognostic Scoring System

• Patient has previously untreated disease, or has received up to one prior treatment regimen for lower-risk Myelodysplastic Syndrome
• Patient has a performance status of equal to or less than 2 on the Eastern Cooperative Oncology Group Performance Scale
• Patient must have adequate organ function

Exclusion Criteria:

• Patient has clinical evidence of Central Nervous System (CNS) leukemia
• Patient is pregnant or breastfeeding, or expecting to conceive within the projected duration of the study
• Patient had prior treatment with a histone deacetylase inhibitor

Merck agreements may vary with individual investigators, but will not prohibit any investigator from publishing. Merck supports the publication of results from all centers of a multi-center trial but requests that reports based on single-site data not precede the primary publication of the entire clinical trial.