A Study of Decitabine Given to Adults With Advanced-Stage Myelodysplastic Syndromes

Inclusion Criteria: 1. Must sign an Institutional Review Board (IRB) -approved informed consent form. 2. Must be 18 years of age or older. 3. Must have a diagnosis for MDS fitting any of the recognized French-American-British (FAB) classifications and International Prognostic Scoring System (IPSS) greater than or equal to 0.5 as determined by Complete Blood Count (CBC), bone marrow assessment, and cytogenetics within 28 days of receiving study drug. If FAB classification is Refractory anemia (RA) or Refractory anemia with ringed sideroblasts (RARS), then must be red cell transfusion dependent, defined as needing red cells more frequently than once every 4 weeks. 4. If receiving erythropoietin(Procrit), must have been on a stable dose for at least 8 weeks before first dose of study drug. 5. If receiving darbepoetin(Aranesp), must have been on a stable dose for at least 12 weeks before first dose of study drug. Exclusion Criteria: 1. Must not have a diagnosis of Acute Myeloid Leukemia (AML) or other progressive malignant disease. 2. Must not have received any investigational agent within the 30 days preceding the first dose of study drug. 3. Must not have uncontrolled cardiac disease or uncontrolled congestive heart failure. 4. Must not have an active viral or bacterial infection.