Sixty four patients who developed acute renal failure at The New York Hospital between July 1981 and June 1982 were studied. The average age was found to be 59.5 years. The overall mortality rate was 62.5%. Patients with non-oliguric renal failure had a lower mortality rate (25%) than those with oliguric renal failure (79%). Those patients with non-oliguric renal failure were more likely to have a discrete cause of renal failure (drugs) and to be in a more stable cardiovascular status. Tachycardia, hypotension, respiratory failure, and documented (or presumed) sepsis all adversely affected prognosis.