Autologous bone marrow transplantation (BMT) is widely performed in both adult and high-risk pediatric acute lymphoblastic leukemia (ALL). Nevertheless, there is still a lack of definitive data concerning its real effectiveness in prolonging the survival of these patients. Between 1984 and 1992, 20 ALL patients in first, second and third complete remission (CR) underwent autografting in the BMT Unit of the University of Milan. This series included 3 children in CR after one or more hematological relapses while all the other patients were adult. Autologous bone marrow was harvested during the same disease phase as that in which the autologous BMT was performed. The conditioning regimen included high-dose Ara-C, cyclophosphamide and TBI 1000 cGy. Successful engraftment occurred in all patients; no early deaths or deaths in CR were recorded, making disease-free survival and event-free survival (EFS) curves superimposable. The overall chance of EFS at 72 months was 41%: 57% for patients in first CR, 53% for patients autografted after one or more isolated meningeal relapse, 14% for patients autografted after one or more hematological relapse. The present data do not provide any evidence to support a role for autologous BMT in prolonging EFS in first CR ALL patients. Nevertheless, the results after meningeal relapse seem to be favourable when compared with the disappointing prospects of these patients after conventional chemotherapy. The EFS after hematological relapse revealed by this study does not significantly differ from that reported in the majority of other studies: the efficacy of autologous BMT in these ALL patients is doubtful.