Cardiovascular risk factors in 566 patients with peripheral arterial disease undergoing major vascular operations were analyzed by chi-square analysis. There were 37 postoperative deaths, for a mortality rate of 8.5%. Cardiovascular complications were responsible for 23 deaths (62%). Five risk factors--congestive heart failure, prior myocardial infarction, prior stroke, arrhythmia, and abnormal electrocardiogram--showed significant individual associations with postoperative cardiovascular complications. A multivariate analysis of these five risk factors and angina led to the development of an equation which predicts the probability of a postoperative cardiovascular complication. The number of complications observed corresponded closely to that predicted by the equation. There was a significantly higher incidence of complications in patients predicted to be at high risk than in those at low risk.