PURPOSE: Primary colorectal signet ring cell carcinoma is a rare disease entity and there is little information compare to ordinary colorectal adenocarcinoma. The aim of this study was to acknowledge the differences of clinicopathological features between colorectal signet ring cell carcinoma and ordinary colorectal adenocarcinoma. METHODS: The author analyzed clinicopathological aspects of 742 consecutive surgical patients with colorectal carcinoma operated at Korean Cancer Center Hospital between January 1993 and December 1999. 19 patients with primary colorectal signet ring cell carcinoma were identified. Clinicopathological features and survival data were evaluated in comparison with those of the ordinary colorectal adenocarcinoma in a retrospective study matched for age, gender, and stage. RESULTS: 19 (2.6%) cases of primary signet ring cell carcinoma were identified and 26 (3.5%) cases of mucinous adenocarcinoma were identified. Male-to-female ratio of the signet ring cell carcinoma was 1.4:1. Mean age was 44 16 years and median age was 41year (range, 22-73 year). No patient had Stage I disease. The majority of patients had an advanced tumor stage at the time of diagnosis (15.8 percents StageII, 68.4 percents Stage III, and 15.8 percents Stage IV). Median survival time was only 29months (P=0.0084). In a study matched for age, gender, and stage, a lower survival rate was found for patients with signet ring cell carcinoma (P=0.0021). In contrast to ordinary adenocarcinoma, signet ring cell carcinoma was characterized by a significantly higher incidence of locoregional recurrence (50%) and peritoneal tumor spread (30%), but a lower incidence of hematogenous metastases (10%). CONCLUSIONS: Primary signet ring cell colorectal carcinoma represents a rare and is frequently diagnosed in an advanced tumor stage, thus showing an overall poorer prognosis than ordinary colorectal carcinoma. A high incidence of locoregional recurrence and peritoneal seeding and a low incidence of hematogenous metastasis are characteristics of signet-ring cell carcinoma. This different pattern of tumor biology would be justified to different management of primary colorectal signet ring cell carcinoma.