Reversible renal impairment has been demonstrated to occur within 9 days of open heart surgery in patients. No increase in serum creatinine or urea was measured in these patients postoperatively. Clonidine administered preoperatively has been reported to improve or prevent a decrease in postoperative creatinine clearance. During cardiopulmonary bypass, no difference in effect on renal function was found between normothermia and hypothermia, alpha-stat and pH-stat, pulsatile and non-pulsatile flow or controlled and uncontrolled mean arterial pressure, in patients with normal kidney function before surgery. Low-dose dopamine, started at induction of anaesthesia and given for 24 h, had no effect on renal function. In recent reports, the mortality in patients needing dialysis for acute renal failure after heart surgery was 76% in adults and 56-60% in children. In patients on dialysis before open heart surgery, the results are much better with mortality rates of 3-16%. Left-ventricular assist, as a bridge to heart transplantation, markedly improved renal function in patients with multiple organ failure.