In a prospective controlled trial, the relative effectiveness of allogeneic bone marrow transplantation and postremission chemotherapy was assessed for adult patients with acute myelogenous leukemia in first complete remission. Twenty-three patients, 15 to 45 years of age, who had an HLA-identical sibling donor were designated to receive bone marrow transplantation. Forty-four patients who either lacked an HLA-identical sibling or were over 45 years of age were designated to receive intensive consolidation chemotherapy. The actuarial rate of leukemia relapse was significantly lower in the transplantation group than in the chemotherapy group (40 +/- 25% [95% confidence interval] compared with 71 +/- 14%, p = 0.01). Actuarial survival at greater than 4 years was not significantly different (40 +/- 21% compared with 27 +/- 14%, p greater than 0.4). These data show that bone marrow transplantation is more effective than consolidation chemotherapy in preventing leukemia relapse, but overall survival was not improved in this study.