Allogeneic bone marrow transplantation was performed in 10 patients with disseminated Burkitt's lymphoma or poor-prognosis T-cell lymphoblastic lymphoma. All patients received a cytoreduction regimen consisting of cyclophosphamide, cytosine arabinoside, bis-chloro-nitroso-urea, and total-body irradiation. Eight patients received marrow from HLA-matched sibling donors. One patient received marrow from a parent donor and one patient died during initial cytoreduction and did not undergo total-body irradiation or marrow infusion. Six patients had Burkitt's lymphoma stages III and IV at diagnosis, and three of the six are alive at 18, 28, and 73 months. Four patients had T-cell lymphoblastic lymphoma, stages III and IV at diagnosis, and two of the four are alive at 29 and 49 months. Overall survival in the nine patients who underwent transplantation is 56 percent by life-table analysis. Follow up for the surviving patients ranges from 18 to 73 months (median 29 months). All five survivors are at home with unmaintained remissions.