Overall survival in 1095 patients with severe acute renal failure (ARF) between 1984 and 1995 was 59.5%. Of these, 107 (16.2%) remained dependent on long-term dialysis. The frequency of end-stage renal failure (ESRF) in survivors of ARF varied between 3% and 41% according to the cause of ARF, being highest in those with acute renal parenchymal disease (in whom survival was also among the highest at 84%) and lowest in ARF due to obstetrics and trauma. Patients failing to regain adequate renal function did not appear to differ on clinical grounds from survivors who became dialysis-independent. Survival in those requiring long-term dialysis was less good than for other patients with ESRF, partly due to excess mortality in those for whom vascular disease or surgery was the precipitating cause of ARF. Six patients recovered sufficient renal function to become independent of dialysis after 3-18 months on regular dialysis therapy (6-21 months after onset of ARF). ESRF resulting from ARF is more frequent than previously reported. This increase may be due to a changing case-mix, increasing age of patients (and hence reduced capacity for renal recovery), and an increase in aggressive surgery for patients with advanced vascular disease. This presents a significant and increasing problem, with implications for both clinical management and the provision of dialysis services.