The aim of this study was to evaluate the use of maintenance chemotherapy after autotransplantation in adult acute lymphoblastic leukemia (ALL), and to compare the relative durability of marrow and peripheral blood stem cell grafts to chemotherapy. Fifty consecutive ALL patients received 200 mg/m2 melphalan alone or 110 mg/m2 melphalan with total-body irradiation in first remission, followed by autologous marrow (ABMT, n = 38) or peripheral blood stem cells (PBSCT, n = 12). After hematologic recovery, 6-mercaptopurine and methotrexate were administered for 2 years. 6-mercaptopurine could be given to 78.9% of ABMT recipients at a median daily dose of 33.5 mg/m2, and to 91.7% of PBSCT recipients at a median daily dose of 44.1 mg/m2. ABMT recipients started 6-mercaptopurine at a median of 58.5 days post-transplant, and PBSCT recipients at 32 days (P = 0.002). 52.6% of ABMT recipients and 75% of PBSCT recipients received weekly methotrexate. No graft failure was seen as a result of chemotherapy. The actuarial 5-year probabilities of overall survival, survival in first remission and relapse were 56.2, 53.2, and 30.6%, respectively. We conclude that administration of maintenance chemotherapy after autografting in adult ALL may reduce relapse. A randomized study is required to evaluate the relative efficacy of PBSCT vs ABMT, and the role of post-transplant maintenance chemotherapy.