BACKGROUND: The aim of this study was to evaluate the clinical course of patients with Wegener's granulomatosis and renal involvement, with special reference to relapse rate, renal and patient survival and morbidity from serious infections. METHODS: A retrospective analysis was carried out of 108 patients presenting with Wegener's granulomatosis and active renal disease in eight hospitals in Norway between 1988 and 1998. Multivariate analysis was used to investigate whether selected variables predicted relapse, renal and patient survival and serious infections. RESULTS: Median follow-up was 41.5 months. Twenty-two patients (20.4%) were admitted with a need for dialysis. Complete remission was obtained in 81.5% after a median of 4 months, and 54.7% relapsed after a median of 22. 5 months. Two- and five-year renal survival was 86 and 75%, respectively, and 22.8% developed end-stage renal disease (ESRD). Two- and five-year patient survival was 88 and 74%, respectively, and the cumulative mortality was 3.8 times higher than expected. The relative risk of relapse increased with the use of intravenous pulse cyclophosphamide compared with daily oral cyclophosphamide. Initial renal function predicted renal survival, and low serum albumin and high age at treatment start increased the mortality risk. Thirty one per cent of the patients were hospitalized for serious infections during follow-up. Old age increased the risk of having an infection. CONCLUSIONS: The current treatment of Wegener's granulomatosis does not prevent relapse, development of ESRD and serious treatment-induced infections in a considerable fraction of the patients. Alternative strategies for the management of this disease will be an important objective for further studies.