Abstract: Allogeneic bone marrow transplantation (BMT) withouta total body irradiation (TBI) conditioning regimen was investigatedin children with juvenile myelomonocytic leukemia (JMML). Eightconsecutive patients with JMML (n = 6) or monosomy 7 (n = 2) underwentBMT at a median age of 20 months. Donor source includedfully matched related (n = 3), mismatched related (n = 2), or fullymatched unrelated (n = 3). The conditioning regimen included busulfan,cyclophosphamide, and etoposide (VP16) (melphalan was substitutedfor VP16 in one patient). The first patient in the series underwentTBI. Graft-versus-host disease prophylaxis was with cyclosporinand methotrexate and in vivo T-cell depletion (Campath 1 g) formismatched and unrelated transplants. Seven and two patients, respectively,received chemotherapy and splenectomy before BMT. Ata median follow-up of 48 months after BMT, five patients remained inremission. The overall survival rate was 63% at 5 years. All deathsoccurred in patients with refractory disease at the time of BMT. AllogeneicBMT without TBI appears to be effective therapy for JMMLand avoids some of the potential late sequelae of TBI in preschoolchildren.