We have assessed the influence of age on the mode of presentation and perioperative mortality in 1033 patients with colorectal cancer. There were 522 patients (51 per cent) over 70 years (group I) and 511 patients (49 per cent) under 70 (group II). In group I, 301 patients (58 per cent) were admitted as emergencies compared with only 222 (43 per cent) in group II (P less than 0.001). Perioperative mortality was especially high in the elderly emergencies, 38 per cent, compared with 18 per cent for elective operations. Of the patients presenting as emergencies in either age group 66 per cent had localized "potentially curable' disease. The incidence of colorectal cancer is highest in the elderly. A larger number of these elderly patients present as emergencies and die from the consequences of complications of localized disease. Earlier diagnosis by pre-symptomatic screening is therefore especially desirable in these old patients.