This ongoing multicentre prospective phase I/II trial enrolled 74 consecutive patients from 22 centres worldwide with severe autoimmune disease, 35 with rheumatological disorders, 31 with neurological, five with haematological and three with vasculitides. They were treated with autologous peripheral blood or bone marrow transplants according to predetermined criteria. Two patients died after mobilisation before transplant. Seventy-two patients were given 73 transplants, seven bone marrow, and 66 mobilised peripheral blood stem cell transplants. The graft was manipulated to remove T and/or B cells in 43 cases. All 73 transplants engrafted. Five patients died of transplant-related complications: two from bleeding, three from infections. Two patients died of progressive disease. The transplant-related mortality at 1 year of 9% (1-17%; 95% CI) is comparable to the transplant-related mortality of 6% (3-9%; 95% CI) in patients transplanted during the same period in Europe for non-Hodgkin's lymphoma in sensitive relapse (P = 0.39). Sixty patients are evaluable for response, 40 patients (65%) showed some improvement in their disease. Haematopoietic stem cell transplants are feasible for patients with severe refractory autoimmune disease. Transplant-related mortality is comparable to results in patients with non-Hodgkin's lymphoma in responsive relapse. Two-thirds of the patients show at least some response. These preliminary data are promising. Although associated with considerable risk, randomised trials comparing autologous stem cell transplants to conventional therapy are warranted.