We evaluated the response to and toxicity of allogeneic or autologous bone marrow transplantation (BMT) for patients with non-Hodgkin's lymphoma (NHL) who relapsed after autologous BMT. Since 1990, 172 patients have received autologous BMTs in NHL at the MD Anderson Cancer Center and 75 have relapsed. Twelve patients (median age, 42 years), with disease recurrence underwent either allogeneic BMT (eight patients) or a second autologous BMT (four patients). Ten patients received thiotepa, busulfan and cyclophosphamide as conditioning, one patient received cyclophosphamide and total body irradiation and one received BCNU, etoposide, Ara-c and melphalan. The median interval between the first and second transplants was 23.5 months (range 5-80 months). Three patients who underwent allogeneic BMT had refractory relapses, three had a responsive relapse and two were in complete response (CR) at the time of BMT. Five patients received peripheral blood stem cells and three patients, allogeneic bone marrow. Three patients are alive and disease-free at 25, 22 and 7 months after allogeneic BMT. Four patients died of treatment-related causes and one from disease recurrence. All four patients undergoing autologous BMT had responsive relapses. Three patients received peripheral blood stem cells and one patient bone marrow. Two patients are alive and disease-free at 12 and 30 months after autologous transplants. There were no treatment-related deaths; two patients died of disease recurrence. This retrospective study shows that in selected patients, allogeneic or autologous BMT is an effective salvage therapy for NHL which recurs after autologous BMT.