Cardiac surgery in elderly patients is associated with acceptable operative mortality but an increased complication rate. Malnutrition is common in the elderly and may adversely affect surgical outcome. To determine the effect of hypoalbuminemia on postoperative complications, 92 patients ≥75 years (range 75 to 90) undergoing a variety of major cardiac surgical procedures were evaluated. Thirteen patients (14%) had a serum albumin level <3.5 g/dl preoperatively. Compared to patients with normal albumin, hypoalbuminemic patients had an increased frequency of postoperative confusion, congestive heart failure, low cardiac output, renal dysfunction and gastrointestinal complications (all p < 0.05). Mean postoperative length of stay was markedly prolonged in these patients (27 vs 12 days; p < 0.001), and mortality also tended to be higher (31 vs 13%; p = 0.11). Using multivariate analysis, albumin <3.5 g/dl was the most powerful predictor of postoperative renal dysfunction (p < 0.01), and was also an independent predictor of increased length of stay (p < 0.01) and gastrointestinal disorders (p < 0.05). Thus, hypoalbuminemia is a powerful indicator of ah increased risk of perioperative complications in elderly patients undergoing cardiac surgery. Increased attention to nutritional factors is warranted in these patients.