-Background -Colorectal cancer is the third commonest cancer in men and the second in women worldwide. Peculiarities of its evolution allow secondary prevention measures through colonoscopy, with high diagnostic and therapeutic capacity. In this context, the quality indicators of the procedure become important, among them the adenoma detection rate (ADR). Objective -To relate the ADR in a medium risk population subjected to colonoscopy with sociodemographic, technical and histopathological indicators. Methods -This was a descriptive, observational and retrospective study whose data were collected from medical records of colonoscopy exams with the indication of colorectal cancer screening or prevention in the period from August to October 2016. Results -A total of 436 exams were included for analysis. Female sex represented 66.3% with 289 patients versus 33.7% for men. Patients aged between 50 and 59 years were 223 (51.1%) and those between 60 and 75 years were 213 (48.9%). In 99 exams (22.7%) chromoscopy was used, and 420 patients (96.3%) were adequately prepared. There were 118 patients with adenomas, resulting in an overall ADR of 27.1%. The ADR for men was 30.6% and 25.3% for women. Patients between 60 and 75 years old had a significantly higher ADR (31.9%, compared to 22.4% of the younger ones). Examinations in which chromoscopy was used also presented higher ADR. Conclusion -The ADR values found for the population of the studied region were compatible with internationally established goals. Continuous evaluation of the ADR may yield interventions aimed at improving quality standards for colonoscopy and promote better prevention of colorectal cancer. HEADINGS -Adenoma. Colorectal cancer. Colonoscopy.