Background : Gallbladder (GB) polyps are now increasingly detected by ultrasonography. We investigated the prevalence and risk factors of GB polyps in health screening population. Methods : An ultrasonographic study of GB polyps were conducted in 35,012 subjects who received a paid health screening examination at Samsung Medical Center. Controls, twice the subjects with GB polyp, were randomly selected from the cases with normal GB. The demographic characteristics and biochemical parameters were recorded. Results : The overall prevalence of GB polyps was 2.94% (1,330/15,573). Among them, 3.63% were men, 2.09% were women. In both males and females, the prevalence was highest in their 40s. The diameter of GB polyps ranged from 2 mm to 20 mm (mean 4.5 mm). Most polyps (98.3%) were less than 10 mm in diameter. Of 1,030 subjects, 64% had a single polyp and 36% had multiple polyps. Multiple logistic regression, with reference group of body mass index (BMI, <22.5 kg/m2), showed odds ratio of 1.074 and 1.864 for BMI groups of 22.5-24.9 and 25 or more respectively. In contrast, other demographic characteristics and biochemical parameters, such as age, smoking, alcohol use, glucose, liver function tests, lipid profiles and HBsAg carriage were lack of any relation to GB polyps. Conclusions : GB polyps are not likely to be rare in Korean adults despite their low prevalence compared to other reports. The body mass index may be a risk factor for GB polyps. (Korean J Med 57:1014-1020, 1999)