Cyclophosphamide has proved to be the most effective therapy for Wegener's granulomatosis, but mortality remains high at many medical centers, and the necessity for giving this toxic agent for many years to prevent relapses remains a major problem. Successful treatment of this disease with sulfamethoxazole-trimethoprim has been reported by DeRemee et al, and experience in a series of ten patients at Thomas Jefferson University Hospital, Philadelphia, confirms its effectiveness. Nine patients are in remission, and the condition of one patient improved. Relapses occurred in four patients after intervals of remission ranging from four to 30 months, but responded to increased doses of trimethoprim in two patients, while two patients required resumption of therapy with cytotoxic agents. Although the effects of sulfamethoxazole-trimethoprim are suppressive rather than curative, its use represents a major advance in treatment of Wegener's granulomatosis, permitting successful treatment of many patients without high toxic doses of cyclophosphamide and prednisone.