PURPOSE: This study was conducted to determine the distributions of the polyp detection rate (PDR) and the adenoma detection rate (ADR) according to age by analyzing the polypectomy results. METHODS: A total of 10,098 patients who underwent a colonoscopy in 2013 were included in this study. Chi-square and logistic regression statistical analyses were performed using SPSS ver. 19. RESULTS: The mean age of the patients was 52.7 years old (median, 54 +/- 12.52 years; range, 14 to 92 years). A total of 6,459 adenomatous polyps (61.7%) from a total of 10,462 polyps were eliminated. The PDR was 50.9% (5,136/10,098), and the. ADR was 35.4% (3,579/10,098). The male-to-female ratio was 51.3%:48.7%, with a male-to-female ADR ratio of 42.8% : 27.7% (P < 0.001). In the age distribution, the values of the ADR were 0% for patients in their 10's, 6.3% for those in their 20's, 14.0% for those in their 30's, 28.7% for those in their 40's, 38.4% for those in their 50's, 46.2% for those in their 60's, 55.8% for those in their 70's, 56.1% for those in their 80's, and 33.3% for those in their 90's. In males, the values of the ADR were 0%, 9.1%, 17.1%, 37.8%, 48.2%, 53.6%, 61.7%, 59.1%, and 33.3% for the same age distribution, and a steep increase was found between patients in their 30's and patients in their 40's. Significant (P < 0.001) factors influencing the ADR included sex, previous colonoscopy experience, polypectomy method, and age of more than 40 years. CONCLUSION: In considering the adenoma carcinoma sequence, 28.7% of people, especially 37.8% of males in their 40's showed adenomatous polyps. Whether an earlier first-time colonoscopy will have better results in preventing colorectal cancer should be investigated and discussed.