ABSTRACT BACKGROUND: Recent studies have shown that endoscopy fellows can perform colonoscopy effectively and safely. However, little is known about the performance of surgical residents without prior knowledge of endoscopic techniques. OBJECTIVE: To assess whether quality indicators were met at an outpatient endoscopy center and whether surgical residents, without prior upper or lower endoscopy skills, could perform colonoscopy adequately. METHODS: A prospective non-randomized cohort study was undertaken. All exams were performed either by assistant physicians or by residents. Quality measures were compared between those groups. RESULTS: A total of 2720 colonoscopies were analyzed. In the resident group, we observed older patients (57.7±12.7 years vs 51.5±14.5 years, P<0.001), a higher prevalence of screening colonoscopies (52% vs 39.4%, P<0.001) and a higher prevalence of colorectal cancer (6.4% vs 1.8%, P<0.001). The cecal intubation rate was higher in the attending group (99.9% vs 89.3%; P<0.001). The polyp detection rate was 40.8%, and no differences were observed between the studied groups. The residents had a higher rate of perforation in all exams (0.4% vs 0%; P=0.02). Postpolypectomy bleeding and 7-day readmission rates were the same (0.2%). All readmissions in 7 days occurred due to low digestive bleeding, and none required intervention. CONCLUSION: Quality indicators were met at a university outpatient endoscopy center; however, medical residents achieved lower rates of cecal intubation and higher rates of perforation than the attending physicians.