Anti-neutrophil cytoplasmic antibodies (ANCA) have been associated with a spectrum of vasculitis that includes granulomatous polyangiitis (formerly known as Wegener's granulomatosis), microscopic polyangiitis, the Churg–Strauss syndrome, primary pauciimmune necrotizing and crescentic glomerulonephritis and related forms of vasculitis. In vitro, in vivo and clinical evidence support the conclusion that ANCA participate in the pathophysiology of this disease spectrum. Rituximab is a potent tool that can interrupt B cell-mediated immunity without major compromise of T cell-mediated immunity. Thus, it has great appeal as a tool to interrupt antibody-mediated autoimmune disease. The results of two prospective randomized trials confirm that rituximab can be effective as part of induction therapy for active ANCA-associated vasculitis. The safety profile for rituximab appears favourable relative to cyclophosphamide and steroids. However, there remain many patients who require individualized adjustments of ancillary therapy, as breakthrough disease, relapses and infectious complications do occur. Based on our current knowledge, rituximab should now be incorporated as part of induction therapy in many patients with ANCA-associated vasculitis. However, more work is needed to determine how rituximab may best be integrated into the overall immunosuppression of these patients.