Eighty-five patients with Wegener's granulomatosis were studied for 21 years at the National Institutes of Health. Patients were treated with a protocol consisting of cyclophosphamide, 2 mg/kg body weight d, together with prednisone, 1 mg/kg body weight d, followed by conversion of the prednisone to an alternate-day regimen. Complete remissions were achieved in 79 of 85 patients (93%). The mean duration of remission for living patients was 48.2 (+/- 3.6) months. Twenty-three patients are off all therapy for a mean duration of 35.3 (+/- 6.3) months without therapy. This study provides a prospective experience with Wegener's granulomatosis and shows that long-term remissions can be induced and maintained in an extremely high number of patients by the combination of daily cyclophosphamide and alternate-day prednisone therapy.