The association between nonleukemic death and various features recorded at presentation in patients with refractory anemia (RA), RA with ring sideroblasts, and RA with excess of blasts was analyzed in 251 patients using the proportional hazards model. Features associated with higher nonleukemic death rates were: 1% or more metamyelocytes in peripheral blood (PB); lower 59Fe incorporation rate; 1% or more blasts in PB; lower hematocrit or hemoglobin; presence of giant platelets; 1 microgram/liter or higher serum vitamin B12 levels; higher periodic acid-Schiff positive erythroblasts; and 1% or higher promyelocytes in PB. Multivariate analysis was also performed using the following predictor variables: metamyelocytes in PB, micromegakaryocytes, hemoglobin, giant platelets, presence or absence of RA with excess of blasts, and mononuclear large megakaryocytes. Patients were divided arbitrarily into low (hazard ratio, less than 0.55), intermediate (hazard ratio, 0.55-1.5), and high (hazard ratio, greater than 1.5) risk groups. The cumulative nonleukemic death rates in the high and intermediate risk groups reached a median at 602 and 1984 days from presentation, respectively, while the rate reached a plateau level of 49.4% after 2644 days in the low risk group. The risk factors for leukemic transformation and nonleukemic death were found to be different and to need separate consideration.