Objective:To retrospectively analyze the clinical characteristics of elderly patients who received colonoscopy and to explore the clinical value of regular colonoscopy for the elderly.Methods:This was a retrospective cohort study.A total of 1 154 patients aged 75 years and over undergone colonoscopy in Guangdong General Hospital from January 2015 to March 2018 were enrolled and divided into three groups, including 605 cases aged 75-79 years, 527 cases aged 80-89 years and 22 cases aged 90 years and over.Detection rates of colorectal lesions by colonoscopy were recorded.The clinical value of annual colonoscopy on the detection of colorectal lesions in elderly patients 75 years and older were analyzed to assess the necessity for regular monitoring.Results:Overall, 569 cases(49.3%)underwent colonoscopy with sedation and 585 cases(50.7%)underwent colonoscopy without sedation.The total positive detection rate was 83.4%(962/1 154), and the main lesions were polyps(858 cases, 74.4%), including 605(52.4%)cases of adenomas.Among the three groups, gastrointestinal bleeding was the main cause for colonoscopy in the group aged 90 years and over, while abdominal discomfort, elevated immunological tumor markers and history of non-colon cancer were the main reasons for colonoscopy in the group aged 75-79 years( P<0.05). A total of 153 cases underwent annual colonoscopy.The detection rate of polyps and adenomas decreased in the second exam, but still higher than 40.0%. Conclusions:Colonoscopy is a safe and effective method for the elderly population aged 75 years and over.Polyps and adenomas are the most common lesions.Recurrence of polyps after colorectal cancer and polypectomy is common and it is necessary to receive colonoscopy regularly.