We assessed the safety and efficacy of autologous stem cell transplantation (ASCT) using T cell depleted grafts in the treatment of severe rheumatoid arthritis. Methods included mobilization 2 g/m2 cyclophosphamide (Cy) and granulocyte-colony stimulating factor; graft manipulation of positive CD34+ and negative T cell selection; and conditioning by 200 mg/kg Cy. All 6 patients improved according to American College of Rheumatology response criteria (one patient ACR70, 2 ACR50, 3 ACR20), but relapsed at 1.5-9 months when they began cyclosporine A (CSA). Five improved (one patient ACR remission, 2 ACR70, one ACR50, one improved but did not satisfy ACR response criteria). No serious complications occurred during ASCT or up to 30 months' followup. There was prolonged reduction in CD4+ T cells. ASCT is safe and has short term efficacy. T cell purging does not prevent relapse. Five patients responded to CSA when their disease had previously been refractory, suggesting an immunomodulatory effect. No serious infectious complications occurred despite prolonged reduction in CD3+CD4+ lymphocytes.