The pretreatment characteristics of nine acute myelogenous leukemia (AML) patients with 8;21 translocation were evaluated to assess their value as prognostic indicators. All patients had AML-M2 according to French-American-British classification. The percentage of eosinophils in the bone marrow (EO/BM) correlated negatively with the percentage of blast cells in the peripheral blood (BL/PB) (p less than 0.05) and positively with complete remission duration (p less than 0.01). Three of the six patients with EO/BM under 5% showed aggressive clinical courses complicated with extra marrow lesions, while the patient with the highest EO/BM was the only one who survived for 5 years. These findings suggest that bone marrow eosinophilia could be useful as a prognostic indicator in AML patients with t(8;21).