Objective: To explore the clinicopathological features and the etiology of colorectal melanosis. Methods： We found 41 cases with colorectal melanosis among 8435 patients who underwent fibercoloscopy and electrocoloscopy in the past 10 years. Results: Colorectal melanosis may have deposition of lipofuscin and macrophages debris containing lipofuscin granules in the tunica propria around the intestinal wall. The mucosal pigmentation often disappears several months after withdrawal of the laxatives. Conclusion:A few patients who suffer from colorectal melanosis are often associated with tumors. The treatment should be concentrated on that to remove the causes of constipation.