Eleven children between the ages of 1 and 16 years with acute non-lymphoblastic leukemia (ANLL) in first remission were included in a study of double unpurged autologous bone marrow transplantation (ABMT). Prior to each ABMT patients received massive chemotherapy with melphalan at a dosage of 140 mg/m2. The first ABMT was done within a median of 4 months after the achievement of complete remission. As soon as the children had adequate hematologic recovery, a second marrow collection was done, followed by a second course of melphalan and a second ABMT. The duration of aplasia was significantly longer after the second ABMT than after the first, but the non-hematologic toxicity was relatively mild in each case and no patient died from the procedure. Four patients relapsed and seven are alive in unmaintained complete remission with a median duration of leukemia-free survival of 29 months (range 15-56 months) after the first ABMT. These data demonstrate the feasibility of repeating ABMT after melphalan in children with ANLL. The eventual impact of such therapy needs to be demonstrated in prospective randomized studies.