There are few controlled trials of immunosuppressive therapy for vasculitis, making the further study of long-term outcome of these diseases with contemporary modes of management necessary. Relapse is frequent in many forms of vasculitis. The consequences of immunosuppressive therapy, including opportunistic infection, have been emphasized. Novel forms of therapy have been described in small series and case reports, although the precise role of such therapies in the treatment of vasculitis in general is far from certain in the absence of collaborative, multicenter controlled studies. The relationship between vasculitis and hepatitis C virus has prompted the use of interferon therapy in the treatment of vasculitic complications resulting from this infection.