context: endoscopic mucosal resection is a minimally invasive technique used in the treatment of colorectal neoplasms, including early carcinomas of different size and morphology. objectives: to evaluate procedure safety, efficacy, outcomes, and recurrence rate in endoscopic mucosal resection of colorectal lesions. methods: a total of 172 lesions in 156 patients were analyzed between may 2003 and may 2009. all lesions showed pit pattern suggestive of neoplasia (kudo types iii-v) at high-magnification chromocolonoscopy with indigo carmine. the lesions were evaluated for macroscopic classification, size, location, and histopathology. lesions 20 mm or smaller were resected en bloc and lesions larger than 20 mm were removed using the piecemeal technique. complications and recurrence were analyzed. patients were followed up for 18 months. results: there were 83 (48.2%) superficial lesions, 57 (33.1%) depressed lesions, 44 (25.6%) laterally spreading tumors, and 45 (26.2%) protruding lesions. mean lesion size was 11.5 mm ± 9.6 mm (2 mm-60 mm). patients' mean age was 61.6 ± 12.5 years (34-93 years). regarding lesion site, 24 (14.0%) lesions were located in the rectum, 68 (39.5%) in the left colon, and 80 (46.5%) in the right colon (transverse, ascending, and cecum). there were 167 (97.1%) neoplasms: 142 (82.5%) adenomatous lesions, 24 (14.0%) intramucosal carcinomas, and 1 (0.6%) invasive carcinoma. en bloc resection was performed in 158 (91.9%) cases and piecemeal resection in 14 (8.1%). bleeding occurred in 5 (2.9%) cases. recurrence was observed in 4.1% (5/122) of cases and was associated with lesions larger than 20 mm (p<0.01), piecemeal resection (p<0.01), advanced neoplasm (p = 0.01), and carcinoma compared to adenoma (p = 0.04). conclusions: endoscopic mucosal resection of colorectal lesions is a safe and effective procedure, with low complication and local recurrence rates. recurrence is associated with lesions larger than 20 mm and carcinomas.