Two patients with high-grade disseminated non-Hodgkin's lymphoma relapsed 3 and 7 months respectively after high-dose chemotherapy and autologous BMT performed in first complete remission. Both patients had an HLA-identical sibling and received an allogeneic BMT 5 and 10 months after autologous BMT, after conditioning with fractionated 12 Gy total body irradiation plus cyclophosphamide. They both are alive and well, with a Karnofsky score of 100%, 15 and 27 months after allogeneic BMT. For selected patients with HLA-identical siblings and good performance status who relapse after autologous transplantation for high-grade non-Hodgkin's lymphoma, allogeneic BMT may be an option.