Backgrounds and aims: The association of melanosis coli with the development ofcolorectal polyps remains uncertain.Methods: From a total of 18263 patients who had received colonoscopy in our hospital,219 with melanosis coli cases and 438 controls matched by age and sex (at 1:2 ratio)were included in this study. The association of incidence, number, location, andpathology of colorectal neoplasm with grades and distribution of melanosis coli wereanalyzed.Results: Melanosis coli was associated with significantly more colorectal polyps thancontrol, a higher incidence of numerous colorectal polyps (number ≥ 20) (7.3% vs0.5%; p < 0.001), and higher number of small colorectal polyps (diameter ≤ 5 mm; p