This trial was designed to study the correlation between peri-operative mortality in patients undergoing elective surgery and the physical status classification of the American Society of Anesthesiologists, the Goldman multifactorial cardiac risk index or the two indices combined. All patients scheduled for elective surgery over a 5-year period were evaluated pre-operatively and were scored according to both indices. Of 16,227 patients studied, 215 died within 4 weeks of operation. Both indices correlated significantly with peri-operative mortality, the ASA grade showing a closer correlation. A regression tree analysis divided the combination groups into five subgroups where the mortality was lowest (0.4%) in ASA grade < or = 2 and cardiac risk index group I (score 0-5 points) and increased up to 7.3% in ASA grade = 4 and cardiac risk index group > or = 3 (score > 13 points). We conclude that for this large number of patients peri-operative mortality can be predicted with the ASA grade and, to a lesser degree, with the cardiac risk index. Applied in the correct way, the combination of the two scores can increase the accuracy of prediction of peri-operative mortality.