RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die.

PURPOSE: Phase II trial to study the effectiveness of decitabine in treating patients with myelodysplastic syndrome.

OBJECTIVES: I. Determine the response of patients with myelodysplastic syndromes (including chronic myelomonocytic leukemia) to decitabine.

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.

PROJECTED ACCRUAL: Approximately 75 patients will be accrued for this study over 1 year.

DISEASE CHARACTERISTICS: Histologically proven myelodysplastic syndrome Refractory anemia (RA) RA with ringed sideroblasts (RARS) RA with excess blasts (RAEB) RAEB in transformation Chronic myelomonocytic leukemia (CMML) RA and RARS: Platelet count less than 50,000/mm3 CMML: If WBC greater than 10,000/mm3, then must have at least 8% monocytes in the blood or marrow

PATIENT CHARACTERISTICS: Age: 15 and over Performance status: Zubrod 0-2 Life expectancy: Not specified Hematopoietic: See Disease Characteristics Hepatic: Bilirubin no greater than 2.0 mg/dL Renal: Creatinine no greater than 2.0 mg/dL Cardiovascular: No New York Heart Association class III or IV heart disease Other: No active or uncontrolled infection Not pregnant or nursing Fertile patients must use effective contraception No other active cancer except skin cancer

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No more than one prior chemotherapy regimen for myelodysplastic syndromes At least 3 weeks since chemotherapy and recovered No prior high-dose cytarabine (at least 0.5 g/m2 for at least 4 doses) Endocrine therapy: Not specified Radiotherapy: Not specified Surgery: Not specified