OUTLINE: This is an open label, multicenter study. Patients are stratified by disease (low risk myelodysplastic syndrome (MDS) vs. high risk MDS vs. chronic myelomonocytic leukemia). Patients receive decitabine as a 4 hour infusion every 8 hours on days 1-3. Treatment continues every 6-8 weeks for 4-6 courses. Patients are followed at 6 and 12 months.