Rapidly progressive glomerulonephritis frequently leads to death or dialysis. In 21 cases treated by plasma exchange and immunosuppression we observed seven deaths, with 12 others progressing to chronic renal failure within 3 months. Patients who died were older than those who survived (57.5 +/- 17.7 vs 40.5 +/- 16.5 years, mean +/- SD, P = 0.05), but had similar clinical symptoms (hypertension, haematuria, proteinuria, extrarenal signs) and biochemical presentation (initial creatininaemia). They required the same degree of haemodialysis, of plasma exchanges and of bolus methylprednisolone. The causes of death were infection (three cases), cardiac arrhythmia (two cases) and gastrointestinal bleeding (two cases). Among the 14 remaining patients, only two recovered normal renal function. Twelve had chronic renal failure, six of them requiring chronic dialysis or transplantation. Severe renal failure at entry and anuria were more frequently observed in patients whose renal function did not improve during treatment. Plasma exchange and steroid bolus infusions also seemed to have a beneficial effect on renal function.