The results in 34 adult patients with acute myeloid leukemia (AML) who have undergone autologous bone marrow transplantation (ABMT) using busulfan and cyclophosphamide (Bu/Cy) in 12 United Kingdom (UK) centers have been analyzed. There were 19 females and 15 males; median age was 40 years (range, 21 to 62 years). Nine patients were in first relapse; 25 were in second remission. The median time of first remission for the whole group was 11.5 months (range, 1 to 56 months). All the patients in first relapse and six patients in second remission received first remission marrow. The leukemia-free survival (LFS) for the patients in first relapse was 33%, with a median follow-up of 20 months. The LFS for the patients in second remission was 48% with a median follow-up of 26 months. The length of second remission exceeds the length of first remission in 14 patients. Considerable toxicity with hemorrhagic cystitis (four patients; none fatal), venoocclusive disease (four patients; one fatal), pneumonitis (four patients; one fatal), intracranial hemorrhage (two patients; two fatal) has occurred. There have been four procedure-related deaths (12%). Hematologic recovery was satisfactory for neutrophils (median time to 0.5 x 10(9)/L, 22 days [range, 11 to 101 days]), but very slow for platelets (median time to 50 x 10(9)/L, 62 days [range, 15 to 1,080 days]). This study suggests that the use of Bu/Cy with ABMT for patients beyond first remission in AML compares favorably with chemotherapy, and although the procedure-related mortality is acceptable, it is associated with protracted platelet recovery.