We investigated whether 'limited' or 'non-renal' Wegener's granulomatosis (WG) differs from classical or 'renal' WG. Renal WG is characterized by necrotizing granulomatosis of the upper and or lower respiratory tract, accompanied by systemic vasculitis and focal segmental necrotizing glomerulonephritis. This last feature is absent in non-renal WG. In a prospective follow-up study of all identified cases presenting to a single teaching hospital, we reviewed 22 patients with non-renal WG, and compared their presentation and outcome with that of 28 patients with renal WG. Clinical and laboratory assessment of disease activity, frequency of death, relapse and end-stage renal disease were assessed. The two groups differed in clinical presentation, laboratory features and outcome. The group with non-renal WG had less cutaneous and pulmonary disease; the haemoglobin, white cell count and platelet count tended to be normal. Residual mortality was confined to the renal group. However, the groups shared many features, particularly their requirement for immunosuppressive therapy, since WG causes major tissue destruction regardless of whether it is a localized or widespread process. At the immunopathological level, the two groups appear to be part of a single disease spectrum. Importantly, the non-renal WG group may change the pattern of their disease to involve the kidney. Long-term follow-up of such patients is therefore essential.