To analyze the efficacy and outcome of colonoscopic resection for colorectal neoplastic lesions, we retrospectively reviewed 338 colorectal lesions from 232 patients regarding the clinical profiles, colonoscopic findings, histological findings, complications, and outcome. Morphologically, these lesions were classified into three categories: pedunculated (n = 140), sessile (n = 176); and flat (n = 22). Histological findings of lesions included adenoma (n = 248), carcinoma in situ (n = 17), submucosal carcinoma (n = 2), hyperplastic polyp (n = 57), and inflammatory polyp (n = 14). Neoplastic lesions are generally larger than nonneoplastic lesions (chi2 test, P < 0.05). The incidence of carcinoma was 5.6% of 338 resected lesions. The rate of cancer or high-grade dysplasia in flat polyps was greater than in pedunculated and sessile polyps (13.6 vs 4.54 vs 5.71%; P < 0.05). There were no perforations or deaths after colonoscopic treatment, and only mild bleeding occured in two patients. To date, 19 patients with early colorectal cancer were treated successfully by endoscopy with no recurrence or metastasis. To reduce the incidence and mortality of colorectal cancer, colonoscopic resection is a simple and safe procedure for removing neoplastic lesions. Detailed histological examinations are essential to decide the indications of surgery.