To determine factors associated with an increased risk of postoperative complications in elderly patients, 60 consecutive patients 75 years of age or older undergoing isolated coronary artery bypass grafting (CABG) were evaluated. Thirty-nine patients (65.0%) had at least one major postoperative complication, including 2 deaths (3.3%). Low body weight was the only univariate predictor (p > 0.05) of an increased likelihood of complications overall. Prior cardiac operation, low serum cholesterol value, and prolonged cardiopulmonary bypass time were associated with increased bleeding. Electrocardiographic evidence of left ventricular hypertrophy was associated with prolonged postoperative confusion. Age of 80 years or more and increased cross-clamp time were predictive of pulmonary dysfunction. Low cardiac output occurred more frequently in patients with nonsinus rhythm, prior cardiac operation, recent congestive heart failure, or elevated level of blood urea nitrogen. Identification of risk factors for specific complications should prompt further studies to define ways of reducing morbidity and the resultant high cost associated with CABG in elderly patients.