OBJECTIVE Concerns regarding the long-term toxicity of daily cyclophosphamide (CP) therapy for the systemic vasculitides have led us to evaluate alternative approaches to treatment in an attempt to achieve comparable efficacy with less toxicity. This study sought to determine the efficacy, toxicity, and immunologic effects of glucocorticoids (GC) and intermittent high-dose intravenous CP ("pulse" CP) in the treatment of 14 patients with Wegener's granulomatosis (WG). METHODS The diagnosis of active WG was supported by a typical clinical presentation and histopathologic findings of vasculitis, granulomatous inflammation, and tissue necrosis. GC treatment was initially provided on a daily basis and later tapered to an alternate-day schedule if vasculitis remained inactive. Pulse CP treatment was initially administered once a month for 6 months. If after 6 months remission had been attained and GC therapy had been discontinued, then pulse CP treatment was given at less frequent intervals thereafter. Treatment and evaluation were provided for participants as inpatients in a clinical research center (National Institutes of Health). RESULTS Thirteen of 14 patients (93%) initially experienced unequivocal improvement with pulse CP therapy, and seven of 14 (50%) achieved remission within 4 months. However, treatment was associated with significant toxicity in two patients and later relapses in nine patients, so that a total of 79% either failed to achieve sustained remission or were unable to continue therapy. Three of 14 (21%) patients have achieved sustained remissions with the pulse CP protocol and one additional patient (who had a limited exacerbation of WG) continues to receive that therapy after 14 to 22 months (mean 17 months). CONCLUSIONS The use of pulse CP and GC therapy in 14 patients with WG was associated with a high initial response rate. However, failure to respond initially to treatment, to sustain improvement, or to tolerate continued treatment was noted in 79% of patients within a period of 1 to 22 months. These observations indicate that this particular pulse CP protocol does not achieve a high degree of lasting efficacy.