2127 patients with operations of the stomach, colon, lungs, vascular system, and amputations were analysed with regard to postoperative mortality and age. There was a striking relationship between age and risk in each group of diseases. The perioperative mortality rate rose from 2.3% in the age group under 50 years to 8.5% in patients between 51 and 70 years of age, and to 18.6% in patients older than 71 years. There was no sex related difference. The causes of death in 219 cases were exactly analysed. Cardiac insufficiency, myocardial infarction, cachexia in malignancies, pulmonary embolism, and renal insufficiency were the main lethal complications in elderly patients.