The incidence and course of acute renal failure following cardiopulmonary bypass (CPB) was retrospectively analyzed. The incidence of oliguric acute renal failure was 1.5% and the mortality rate was 27%, a figure substantially lower than previously reported. Both peritoneal dialysis and hemodialysis were initiated early, with a mean of 3.6 days between the onset of acute renal failure and initiation of dialysis. Survivors had a mean duration of acute renal failure of 24 days. Deaths were caused by cardiac failure (one) and sepsis (two). Mortality rate from acute renal failure complicating CPB resembles that from acute renal failure related to other causes and may be lowered by early aggressive dialysis.