Between May 1984 and May 1992, 75 children 3-19 (median 9) years of age underwent autologous marrow transplant. Clinical data were obtained from the BMT Registry of the AIEOP (Italian Association of Pediatric Hemato/Oncology). Fifty-six children were transplanted after marrow +/- other site(s) relapse and 19 after an isolated extramedullary relapse. The transplant preparative regimens varied according to the center performing the transplant. Seven patients (9%) died of transplant-related complications. Forty-four (58.6%) of 75 patients relapsed again following autologous BMT. The 5-year DFS was 27.8%. An isolated extramedullary relapse was the only variable that statistically influenced DFS. In this retrospective study, autologous BMT for patients with ALL in second CR following marrow relapse did not offer an encouraging result (13% probability of DFS at 5 years), whereas autologous BMT following an (early) isolated extramedullary relapse resulted in nearly 70% DFS. Autologous BMT may be appropriate for this latter group of patients.