We have prospectively compared the values of autologous BMT (auto-BMT) and allogeneic marrow transplantation (allo-BMT) in patients (age 15-60 years) with acute myeloid leukemia (AML) who attained complete remission (CR) following remission-induction therapy. In 90/117 cases CR was reached. In 32 of those complete responders auto-BMT was undertaken and in 21 eligible cases HLA-matched allo-BMT. AML relapse was the predominant cause of failure after auto-BMT (17/32). The incidence of relapse after allo-BMT was 6/21. Patients treated with auto-BMT and allo-BMT have an overall survival of 37% and 66% at 3 years posttransplant (P = 0.05). Survival of the nongrafted complete responders is less than 10%. Allo-BMT in adult patients with AML in first complete remission provides a superior outcome when directly compared with the results of auto-BMT.