Mucinous carcinomas accounted for 37 (6.4%) of 540 cases of colorectal carcinoma. The clinical and pathological features of these mucinous carcinomas were compared with those of the 510 well or moderately differentiated adenocarcinomas. Mucinous carcinoma was more common in the patients 39 years of age or under (P less than 0.05) and was more frequent in the female patients. A large number of mucinous carcinomas were located in the rectum, followed by the right colon. However, the right colon showed a higher relative incidence (40.5% vs 12.5%, P less than 0.005). Mucinous carcinoma was characterized by infiltration of the surrounding tissues (24.3% vs 7.8%, P less than 0.005), positive lymph node involvement (75.7% vs 48.6%, P less than 0.005), and peritoneal implant (21.6% vs 4.1%, P less than 0.005). The cumulative five and ten year survival rates after resection of mucinous carcinoma were 45.5 per cent and 39.8 per cent, respectively, and those after curative resection, 72.4 per cent and 63.5 per cent, respectively. These survival rates were lower, without significant differences, than those for the well or moderately differentiated adenocarcinomas. The results suggest the need for aggressive lymph node dissection and wide excision of the surrounding tissues for mucinous carcinoma, with special attention paid to local recurrence.