This multicenter, open-label study evaluated the efficacy and safety of decitabine in patients from Argentina and South Korea with myelodysplastic syndromes or chronic myelomonocytic leukemia. Of 106 patients who received decitabine 20 mg/m² intravenously over 1 h once daily for 5 days in 4-week cycles, 99 patients were evaluable after receiving at least two cycles. The overall improvement rate was 35% (19% complete response +4% marrow complete response +4% partial response +8% hematologic improvement). Overall survival at 2 years was 71%. Treatment-related adverse events included febrile neutropenia, thrombocytopenia and bleeding, asthenia, fatigue, and eosinophilia. After complete response (CR), three patients received an allogeneic stem cell transplant. Four patients who relapsed after CR responded to decitabine retreatment. Acute myelogenous leukemia developed during follow-up in 21% of patients. Decitabine in a 5-day outpatient administration schedule was effective and well tolerated in typical clinical practice settings in South America and Asia.