PURPOSE: Detecting and treating early colorectal cancers are most important for preventing advanced colorectal cancers which are difficult to manage. However, there is still a lack of data and guidelines in Korea about early colorectal cancers, especially when endoscopy is concerned. This study was undertaken in an effort to gather information in this area. METHODS: We experienced 107 early colorectal cancers from 1995 to 1998. We analyzed them with special reference to endoscopic characteristics and treatment. Ninty-six cases were followed for an average of 17 months. RESULTS: Ninty-four (87.9%) of the early colorectal cancers were detected during the last two years of the study. The male-to-female ratio was 2.1 to 1. The most common age group was the 7th decade. The rectum and the sigmoid colon were involved in 85% of the early cancers. Lesions smaller than 20 mm accounted for 54.2% of the early cancers and ones smaller than 10 mm 15%. There were no malignancies in flat-elevated lesions smaller than 10 mm; to the contrary, there was a 66.7% malignancy rate in depressed lesions. Malignancy developed in LSTs (Laterally spreading tumors) larger than 20 mm. Regarding configuration, protruded-type tumors accounted for 80.4% of the lesions, depressed-type tumors 5.6%, and LSTs 4.7%. The most common endoscopic characteristic of early colorectal cancer was redness. White spots, hardness, easy bleeding upon touch, and nodules were recognized in more than 20% of the tumors; depression and erosion were noticed in more than 10%. An expanded figure, convergence of mucosal folds, a whitish patch, and ulceration were useful in some cases. The submucosal cancer rate was 30.2% in protruded-type lesions and 66.7% in depressed-type ones. The overall adenoma-association rate was 93%. All lesions without an adenomatous component were submucosal cancers. The overall endoscopic resection rate was 87.9%. Among them, those who needed additional surgical resection accounted for 13.8% (13/94). Three recurrences were recognized. Those three were all early rectal cancers associated with villous tumors and were larger than 20 mm. All recurrences were treated endoscopically. There was one case of bleeding within 1 day after endoscopic resection. That was associated with a 20-mm, pedunculated lesion in the ascending colon and was treated using a detachable snare. CONCLUSIONS: It is important to recognize the endoscopic characteristics of early colorectal cancers, especially those of depressed lesions and LSTs. Those characteristics are also useful in selecting appropriate candidates for endoscopic resection.