BACKGROUND/AIMS: Recently, early detection and treatment of early colon cancer (ECC) has increased, and the concept of de novo carcinogenesis of colon cancer was introduced. However there were few studies in Korea. So we tried to find the incidence of ECC and the possibility of de novo colon cancer (DCC) in Korea. METHODS: From Jun 1995 to Jun 2003, 3072 patients who first treated as colon cancer at Samsung Medical Center were enrolled. We selected ECC by medical record review, and pathologic slides and endoscopic photos were reviewed to evaluate the underlying tissue of cancer focus and morphologic characteristics of ECCs. ECC was defined as the cancer confined to mucosa or submucosa, and DCC was defined as the cancer lesser than 1 cm but had no adenoma component. RESULTS: The 192 patients (6.3%) had 196 cases of ECC. The ratio of mucosal and submucosal (SM) cancers was 36.7%:63.3%. The protruded type was the most frequent type (82.1%). The depressed type was the smallest (12.9+/-6.3 mm), in size and 100% showed and SM involvement. It has significantly higher rate of the cancer without underlying adenoma component (57.1%, p<0.001). The DCC were 6 cases and all were SM cancer and had 3 cases of protruded and depressed type each other. CONCLUSIONS: The most common shape of ECC was protruded type. However, depressed type was smaller and had higher rate of SM involvment and no adenoma component around the cancers. And we found some of DCC although the frequency was very low.