Rituximab is a genetically engineered chimeric monoclonal immunoglobulin (Ig)G1 antibody. It binds the CD20 trans-membrane surface antigen expressed by mature B cells but not by antibody secreting plasma cells, and removes the cells by activating complement, inducing cell-mediated lysis, and by apoptosis. Mainly used for the treatment of non-Hodgkin's lymphomas, rituximab has recently been tried with favourable responses in rheumatoid arthritis, systemic lupus erythematosus, and other chronic immunological diseases. Wegener's granulomatosis (WG) is a granulomatous vasculitis with high morbidity and mortality. It is thought that anti-neutrophil cytoplasmatic antibodies (ANCA) with specificity for proteinase 3 (PR3) are possibly involved in the pathogenesis of the disease. Conventional therapy with cyclophosphamide and corticosteroids generally succeeds in inducing remission, but relapses frequently follow. Among the biological agents, tumour necrosis factor-alpha (TNF-alpha) inhibitors have been tried with some success. Based on a case report we recently treated three refractory WG patients with rituximab and achieved almost complete but temporary remission. CD20+ cells disappeared rapidly in peripheral blood, only to rise prior to subsequent disease flares occurring at 34, 63, and 54 weeks, respectively (Figure 1). A new flare occurred in one patient at 86 weeks. At the end of the observation periods (54, 102, and 120 weeks), only one patient had proteinuria. Chest radiographs became normal in two patients, while infiltrates remained unchanged in the third. Granulomatous retro-orbital or sinus masses in two patients seemed unresponsive to therapy.