OBJECTIVE Small colorectal polyps are encountered frequently and may be incompletely removed during colonoscopy. The optimal technique for removal of small colorectal polyps is uncertain. The aim of this study was to compare the incomplete resection rate (IRR) by using EMR or cold snare polypectomy (CSP) for the removal of small adenomatous polyps. METHODS This was a prospective randomized controlled study from a tertiary-care referral center. A total of 358 patients who satisfied the inclusion criteria (polyp sized 6-9 mm) were randomized to the EMR (n =179) and CSP (n =179) groups, and their polyps were treated with conventional EMR or CSP, respectively. After polypectomy, an additional 5 forceps biopsies were performed at the base and margins of polypectomy sites to assess the presence of residual polyp tissue. The EMR and CSP samples were compared to assess the IRR. RESULTS Among a total of 525 polyps, 415 (79.0%) were adenomatous polyps, and 41 (16.4%) were advanced adenomas. The overall IRR for adenomatous polyps was significantly higher in the CSP group compared with the EMR group (18/212, 8.5% vs 3/203, 1.5%; P = .001). Logistic regression analysis revealed that the CSP procedure was a stronger risk factor for the IRR (odds ratio [OR] 6.924; 95% confidence interval [CI], 2.098-24.393; P = .003). In addition, piecemeal resection was the most important risk factor for the IRR (OR 28.696; 95% CI, 3.620-227.497; P = .001). The mean procedure time for polypectomy was not significantly different between the EMR and CSP groups (5.5 ± 2.7 vs 4.7 ± 3.4 minutes; P = .410). None of these patients presented with delayed bleeding. There were no severe adverse events related to the biopsies. CONCLUSIONS EMR was significantly superior to CSP for achieving complete endoscopic resection of small colorectal polyps. Patients with piecemeal resection of polyps had a higher risk for incomplete resection. (Clinical trial registration number: Hongwei-1102-12.).