AIM: to assess the safety of endoscopic piecemeal mucosal resection (EPMR) of large epithelial colorectal lesions and to identify risk factors for tumor recurrence.PATIENTS AND METHODS: results of EPMR were evaluated in retrospective study, which was carried out in five regional endoscopic centers. The criterion for inclusion in the study was benign colorectal lesion of 20 mm and larger.RESULTS: we found that complications of EPMR occurred in 13% of cases. In 9.2% it was intraoperative bleeding, which was stopped endoscopically. Postoperative bleeding was detected in 1.2% of patients, perforation – in 2.4%. Tumor recurrence developed in 12%. We have revealed a direct correlation between tumor recurrence and intraoperative bleeding (p=0.013) and a size of lesion >4 cm (p=0.012); the inverse correlation between the tumor recurrence and the fullness of the lifting during the removal (p=0.008) and the male gender of the patient (p=0.043).CONCLUSION: significant risk factors of tumor recurrence after endoscopic piecemeal resection of large benign colorectal neoplasia were identified before the procedure (gender and tumor size) and intraoperatively (completeness of lifting and the intraoperative bleeding).