The development of renal failure during respiratory failure is of grave prognostic significance. In 686 patients with respiratory failure, 74 developed renal failure; these had a mortality of 80%. The leading predisposing factors are: 1) gastrointestinal bleeding with hypovolemic shock; 2) sepsis with shock; 3) drug induced nephrotoxicity; and 4) hypotension. With antacid gastric neutralization, judicious use of nephrotoxic antibiotics, the incidence of renal failure can be reduced. Once renal failure occurs, early dialysis may increase the chances of recovery in these critically ill patients.