The authors examine prospectively the results of a single surgeon (H.S.S.), using a computerized database to determine the effect of age on morbidity and mortality in the management of colorectal cancer. Computer input was performed by a nurse data manager (20 minutes per patient), and data retrieval required approximately 30 minutes of computer time. Between 1984 and 1989, 241 patients with primary colorectal cancer underwent operation. The average age was 67.9 years (range from 31 to 94 years). The authors compared 108 (44.8%) patients who were older than 70 years with 133 (55.2%) patients who were 70 years of age or younger. Rectal carcinoma was more common in the younger age group (41.3% v. 20.4%), but right-sided carcinoma was more common in the older age group (36.1% v. 19.6%, p less than 0.001). Bleeding was more frequent in the younger patients than in the older ones (51.9% v. 35.2%, p less than 0.01). There was no difference between the two groups in tumour staging, using the modified Dukes' classification. The overall mortality was 2.5% and morbidity was 39.4%, with no significant differences between the groups. The authors conclude that age should not be a determinant in consideration of operation for colorectal cancer and that a personal computerized database facilitates simple prospective studies.