Allogeneic bone marrow transplants (BMT) in acute lymphoblastic leukemia following cyclophosphamide (Cy) and total body irradiation (TBI) has resulted in disease-free survival (DFS) for CR1, CR2, and CR3 of 10/18 (56%), 16/30 (53%) and 4/17 (24%), respectively. Median follow-up of survivors was 25-43 months. One relapse was seen in CR1, 1 in CR2, and 6 in CR3. Allogeneic BMT in acute nonlymphoblastic leukemia (ANLL) following busulfan (Bu) resulted in DFS for CR1, CR2 + CR3 + early relapse of 21/47 (45%) and 13/41 (32%), respectively. Median DFS of survivors of all groups together was 36 months. DFS of all patients 20 years or less was 15/27 (56%) and 19/61 (31%) for ages 21-46. Three relapses of 47 (6%) were seen in CR1 and 6/41 (15%) in subsequent remission and early relapse. BMT of autologous BMT with 4-hydroperoxy-cyclophosphamide (4-HC) purged marrow in ANLL in CR1 (5), CR2 (32) and CR3 (9) following Bu + Cy resulted in DFS of 19/46 (41%) for 1-67 months (median 15 months). Twenty patients with prior risk non-Hodgkin's lymphoma received 4-HC-purged marrow following Cy + TBI. DFS was 10/20 (50%) for 1.4-9.5 years (median 2.9 years).