Analysis of the clinical and autopsy reports of 200 deaths following surgery for colorectal cancer from 1956 to 1974, at the Dept. of Surgery, University of Heidelberg, revealed that pneumonia (24.5%) was the most common cause of death followed by peritonitis (22%), pulmonary embolism (15.5%), advanced tumor disease (14%), cardiac failure (9.5%), ileus (5.5%), and others (9%). The explanation for the postoperative mortality rate of 12% (cancer of colon) and 13.2% (cancer of rectum) lies in the fact that 82.5% of those who died postoperatively were beyond the age of 60, and 40.5% beyond 70 years at the time of surgery. Moreover, in 50.5% advanced tumors with regional and/or distant metastases were found. In 55.5% severe preoperative complications (ileus: 38%, peritonitis: 11%, abscess formation or hemorrhage: 6.5%) required an emergency operation. Only 38.5% of the procedures were considered for cure. Besides the need for early recognition of the cancer, intensification of pre- and postoper treatment appears to be the predominant task in the effort to decrease postoperative mortality.