The prognosis of colorectal cancer in the elderly was examined in a study of 306 consecutive patients. The patients were divided into two groups: Group 1 included 171 patients of average age 77 years (range 70-97); Group 2 comprised 135 patients of average age 59 years (range 22-69). There was no significant difference between the two groups with regard to the mode of presentation, the location and Duke's classification of the tumours, the incidence of palliative operations, and the perioperative mortality. The surgical mortality rates in Group 1 were 6 per cent overall, 4 per cent after elective operations, and 16 per cent after emergency surgery; the corresponding mortality rates for Group 2 were 3 per cent, 1 per cent, and 20 per cent. Emergency surgery was associated with a significantly higher incidence of perioperative death at any age (P less than 0.001) and most deaths resulted from complications of coexisting medical disorders or thrombo-embolic complications. Crude actuarial 5-year survival curves showed an increased death rate in Group 1 after 18 months and a significantly lower 5-year survival (P less than 0.05) but the age-corrected survival curves for the two groups were not significantly different, and it was concluded that the prognosis for colorectal cancer in the elderly is not significantly different from that of younger patients.