The purpose of this report is to analyze the clinicopathologic features of colorectal mucinous adenocarcinoma (MC), which is generally believed to have a poor prognosis, in an attempt to assess ways in which the surgical outcome can be improved. Clinicopathologic features of 44 patients with MC (6.6%), from among 662 patients with primary colorectal cancers, were compared with those of 545 patients with nonmucinous (non-MC) adenocarcinoma. MC is more likely to invade the adjacent viscera (29% versus 10%, p < 0.005) and show more extensive lymph node involvement beyond the pericolonic region (50% versus 26%, p < 0.005) than non-MC. Based on these findings, a more aggressive attitude toward surgical intervention is recommended, including extensive lymph node dissection and the resection of adjacent organs that seems to be affected macroscopically, to improve the surgical outcome of this clinical entity.