A comparative analysis has been made of the results of surgical management of single carcinomas of the colon and rectum in a series of 1939 patients treated by one surgeon. The data were prospectively collected, with 99 per cent follow-up. Cancer specific survival did not differ significantly between patients with colonic or rectal cancer. Survival prospects were better for women (P = 0·02) and for patients less than 40 years of age (P = 0·03). Survival was significantly related to tumour staging (P<0·001). Cancer specific survival was better after curative resection for colonic than rectal carcinoma (P = 0·003). Five-year survival for patients with colonic tumours was 76 per cent and for rectal tumours 69 per cent. The 10-year survival figures were 73 per cent and 61 per cent respectively. This difference was accounted for by a higher proportion of Dukes' stage C tumours in the rectum (P<0·001) and better survival prospects for colonic compared to rectal stage C1 tumours (P = 0·02). Sphincter-saving resections were performed in 64 per cent of rectal cancer patients managed by curative resection. Survival tended to be better than after sphincter-sacrificing operations. After palliative resection, median survival for colonic and rectal cancer was 14 and 13 months respectively. After palliative bypass operations the corresponding figures were 4 and 8 months.