Twenty-five adult patients, 19 males, six females, age 16-43 years (median 23), with lymphoblastic lymphoma received allogeneic or autologous bone marrow transplantation in first complete remission. Twelve patients were Murphy stage IV with bone marrow and/or CNS involvement and 13 were stage III of whom nine had thoracic involvement. Complete remission was achieved with an intensive anthracycline containing multiagent chemotherapy protocol. Twelve patients with an HLA identical sibling received an allogeneic marrow and 13 without a donor received their own marrow harvested a median of 2 months (0-4 months) after complete remission and purged in vitro with either mafosfamide (eight patients) or anti T-cell monoclonal antibodies and complement (three patients). Bone marrow transplantation was performed 1-7 months (median 3 months) after achieving first complete remission. The conditioning regimen consisted of cyclophosphamide or high dose melphalan and total body irradiation. The actuarial 4-year disease-free survival is 68% (+/- 9% SE). The actuarial probability of relapse was 26% (+/- 3% SE) with a median follow up to 22 months. There was no difference between allogeneic and autologous transplantation with eight out of 12 allo patients in first continuous complete remission 26-45 months after transplant and nine out of 13 auto in continuous complete remission 15-75 months after transplant. These results compare favourably with those achieved with the best chemotherapeutic regimen used for such patients.