From October 1984 to December 1994, 142 patients from six IGCI-BMT centers (78 acute myelogenous leukemia and 64 acute lymphoblastic leukemia) received allogeneic bone marrow from their HLA-identical sibling. The probability of LFS at 60 months is 41% for AML patients and 39% for ALL patients. A better LFS was documented in patients allografted in first CR compared to the patients treated in advanced stage of the disease. The overall relapse rate is 27% for AML patients and 45% for ALL patients. The relapse rate is higher for patients allografted in advanced stage of the disease (47 vs 26% at 60 months for AML and 55 vs 38% at 60 months for ALL). The incidence of moderate to severe acute GVHD is between 45-50% for both AML and ALL patients. Chronic GVHD was documented in 30% of AML patients and 38% of ALL patients. Transplant-related mortality for both AML and ALL is about 25%. Relapse and GVHD with or without infection are the main causes of death. These results confirmed that allogeneic BMT is very effective therapy for patients with acute leukemia, especially for patients transplanted in first CR.