Inclusion Criteria:

• Patients with MDS and > 5% blasts or IPSS risk intermediate or high; patients with CMML; patients with AML who are age 60 or older. No prior intensive chemotherapy or high-dose ara-C (> 1g/m2). No prior azacytidine for 3 cycles or more or prior decitabine for 2 cycles or more. Prior biologic therapies, targeted therapies, or single agent chemotherapy allowed. Patients must have been off chemotherapy for 2 weeks prior to entering this study and recovered from the toxic effects of that therapy, unless there is evidence of rapidly progressive disease.
• Continued from #1: Hydroxyurea is permitted for control of counts prior to treatment. Procrit, GCSF are allowed before therapy. Procrit, GCSF or other growth factors are permitted on therapy. Use of hydroxyurea with rapidly proliferative disease is allowed for the first two weeks on therapy.
• Performance 0-2 (ECOG). Adequate liver function (bilirubin of < 2mg/dl) and renal function (creatinine < 2mg/dl). Adequate cardiac functions (NYHA cardiac III-IV excluded). ALT < 2.5x institutional upper limit of normal.
• Signed informed consent.

Exclusion Criteria:

• Nursing and pregnant females. Patients of childbearing potential should practice effective methods of contraception. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.
• Active and uncontrolled infections.
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, or psychiatric illness/social situations that would limit compliance with study requirements.
• Known ornithine transcarbamylase disorder.
• Patients requiring continuous valproic acid treatment for the control of seizure disorders.