Introduction. Colonoscopy is the gold standard for the diagnosis of diseases of the colon and rectum and the primary prevention test for colon cancer. The main indicators of quality in colonoscopy are the rate of complete colonoscopy and the rate of detected adenomas. Objectives. We aimed to know the rates of cecal intubation and detection of adenomas and to identify factors related to these two quality indicators in colonoscopies performed in the Peruvian Japanese Policlinic during 2007. Material and methods. A correlational cross-sectional and retrospective study was performed. Data were collected from the colonoscopies performed by 10 endoscopists in the Peruvian Japanese Policlinic during 2007. Results. We included 843 colonoscopies. Cecal intubation was achieved in 801 patients (95%). The multivariate analysis found that cecal intubation was correlated with the type of sedation/analgesia and the quality of bowel preparation. At least one adenoma was detected in 168 colonoscopies (19.9%). Multivariate analysis found that age, colonic cleansing and time of withdrawal were factors significantly associated with the detection of adenomas. Conclusions. The quality of colonoscopy depends on several factors: bowel preparation, type of sedation/analgesia and time of withdrawal. These are the targets on which we can act to improve performance.