BACKGROUND AND OBJECTIVE: To assess the value of rituximab in systemic autoimmune diseases which are refractory to others treatments. PATIENTS AND METHOD: Prospective study on 12 patients -7 with systemic lupus erythematosus (SLE), 4 with Wegener's granulomatosis (WG), and 1 with overlapping connective disease and autoimmune thrombocytopenia-, controlled in a specialized unit of a tertiary hospital. Four weekly doses of rituximab, 2 biweekly doses of cyclophosphamide, and glucocorticoids were administered to all patients, and other immunosuppressants were also administered as considered necessary in each case. RESULTS: Mean follow up after treatment with rituximab was 12.8 moths for SLE patients and 12.3 for WG patients. In SLE patients, proteinuria was reduced below 1 g daily in 5 cases (83%), with a clear parallel improvement in the urinary sediment. Serositis was resolved in both cases. One patient required 3 treatment cycles to obtain an adequate response and another required a second cycle for relapse. Only one patient with WG had a favorable response. The patient treated for autoimmune thrombocytopenia had a favorable response, with no relapses, and creatine-kinase levels also tended to return to normal. There were 2 serious adverse events (terminal renal failure and serious colitis in a patient with SLE, and death of one patient with WG), that were not adjudicated directly to rituximab. Immunoglobulin levels did not change substantially. There were no infusion reactions or associated infections. CONCLUSIONS: Rituximab was useful in patients with SLE refractory to other immunosuppressants. On the contrary, its efficacy in WG was limited. The response of thrombocytopenia was complete and maintained.