PURPOSE: To establish the CT findings and clinical characteristics of colorectal mucinous adenocarcinoma. MATERIALS AND METHODS: The CT features of 26 surgically proven cases of colorectal mucinous adenocarcinoma were reviewed. The subjects were selected from among 262 patients with colorectal cancer, of whom 40 with non-mucinous adenocarcinoma were included as a control group. Contrast-enhaneed CT images were analyzed for tumor location, the presence or absence of tumoral calcification, tumor shape (circumferential or eccentric, polypoid or infiltrative), tumor thickness-to-length ratio, and attenuation and homogeneity. In each group, the TNM stage of pathologic specimens was compared. During follow-up, the incidence of recurrence, and outcome, were also compared. RESULTS: CT images of mucinous adenocarcinoma revealed intratumoral calcification in three patients (12%, p < 0.01). Tumors were eccentric and polypoid-shaped, with a high tumoral thickness/length ratio (p < 0.01). On contrast-enhanced images, most were seen as a heterogenous hypoattenvuted mass. No differences in T-NM stage were found in surgical specimens. In patients with mucinous adenocarcinoma, recurrence during the early follow-up period is more common than in patients with non-mucinous cancer. CONCLUSION: Contrast-enhanced CT reveals mucinous adenocarcinoma as an eccentric polypoid mass with heterogeneous hypoattenuation. In patients with mucinous colorectal cancer, careful follow-up is required because tumors tend to recur early in the follow-up period.