We have treated 28 patients (pts) with malignant hematological diseases with allogeneic bone marrow transplantation (BMT). 18 pts had acute lymphoblastic (ALL) and non lymphoblastic leukemia (ANLL), 5 chronic myeloid leukemia (CML), 2 severe aplastic anemia (SAA), 1 myelodisplasia, 1 Fanconi's anemia and 1 advanced Non Hodgkin's lymphoma. All but three received the graft from HLA identical sibling donors. We used conditioning with total body irradiation and chemotherapy (cyclophosphamide, cytarabine and etoposide) in 17 pts and chemotherapy alone in 11. 24 pts had full hematological recovery 18 to 25 days post BMT. 15 pts died after BMT as a consequence of toxicity or early infection (4), graft failure (2), graft versus host disease (4) or relapse (5). Actuarial event free survival for the group with favorable prognosis (SAA, ALL and ANLL in first or second remission and CML in chronic phase) is 57% at 36 months. Allogeneic BMT is an effective and feasible therapeutic procedure for selected patients with hematological malignancies.