Aim To determine the incidence and endoscopic types of colorectal lesions diagnosed with colonoscopy in elderly patients. Methods Consecutive Japanese patients who underwent colonic endoscopy between 1994 and 2007 (n = 5145; 2245 men and 2900 women, age 20–101 years) were examined retrospectively. Correlations between age, sex and number of lesions were analyzed. Results The incidence of advanced tumors was significantly correlated with increasing age in men (P = 0.02), and tumors were detected mainly in the sigmoid colon and rectum in both sexes. Right‐sided colon cancer was significantly more common in women compared with men (P < 0.001). Polyps were detected throughout the colon, and their incidence was correlated significantly with increasing age in women (P = 0.01). Diverticula were frequently detected in the ascending and sigmoid colon in both sexes. Left‐sided diverticula were significantly more common in women compared with men (P < 0.001). Lateral spreading tumors were detected mainly in the cecum in both sexes. Though the number of cases with angioectasia was small, angioectasia was slightly more common in the cecum and the ascending colon in women. Conclusions In the present study, the incidence of advanced tumors correlated with increasing age in men, and right‐sided cases were significantly more common in women than in men. The incidence of polyps correlated with increasing age in women. Left‐sided diverticula were significantly more common in women than in men. Geriatr Gerontol Int 2016; 16: 1319–1323.