Nine acute myelogenous leukemia(AML) patients with a translocation 8;21, who were treated at Keio University Hospital between 1983 and August 1990, were reviewed. All of them were classified into AML-M2 subtype of the French-American-British classification. It formed 43% of all M2 cases. The patients' mean age was 47 years. Neutrophil alkaline phosphatase score was lower than normal and complete remission(CR) was achieved in all cases. In statistical analysis, patients with the t(8;21) showed a longer CR duration and a higher percentage of eosinophils than the other AML-M2 patients without this karyotype (p less than 0.05, p less than 0.01, respectively). As an additional chromosomal abberation, two patients showed a loss of Y chromosome at first diagnosis and another patient did a deletion of 12p at the 3rd relapse and an elongation of 20q in addition to the 12p- at the 4th relapse. Although patients with the t(8;21) are regarded as a favorable group in respect of survival, we found a subset of patients who had poor prognosis. Some of them were accompanied with solid tumor formation. Only one patient has lived longer than 5 years. These findings suggest that AML with the t(8;21) is clinically heterogenous.