Twenty-one patients with non-Hodgkin's lymphoma (NHL) felt to be incurable with conventional chemotherapy underwent high-dose chemo +/- radiotherapy and allogeneic sibling donor transplant. The median patient age was 27 years (range 6-47 years); 13 were male and 8 female. By the working formulation, 6 patients at diagnosis had low-grade NHL, 8 intermediate-grade, and 7 high-grade disease. Three patients were in first remission at transplant, 3 in an advanced remission, 5 had failed to respond to initial therapy while 4 had a partial response to initial therapy, and 6 were in relapse (first or beyond). Sixteen patients were conditioned with cyclophosphamide, etoposide and total body irradiation (TBI), 4 with cyclophosphamide and TBI, and one with a combination of busulfan, melphalan and cyclophosphamide. GVHD prophylaxis was variable. At last follow-up, 8 of 21 patients remain alive and progression-free at a median of 37.5 months (range 6-58 months); actuarial event-free survival is 38% (95% confidence interval 17-58%). Thirteen patients died at a median of 2 (range 0.5-8) months post-BMT, 5 from regimen-related toxicity, 3 from acute GVHD, 2 from infections related to chronic GVHD and 3 from disease progression. Factors which were adverse predictors of progression-free survival included low-grade disease, presence of B symptoms at BMT, Karnofsky performance status at BMT and female sex. We concur with previous workers in concluding that allogeneic BMT may offer effective therapy for selected patients with incurable NHL. Major issues to be considered include timing of BMT and disease status at BMT.