Background/Aims: A number of studies have shown an increased prevalence of gallstones in patients with coronary heart diseases. Since it has also been known ihat the high density lipoprotein cholesterol(HDL-C) is an important protective factor against coronary artery diseases, one may speculate the possibility that HDL-C may play a role in preventing the gallstone formation, so we tried to identify this role of HDL-C. Methods: We analysed 165 patients who received cholecystectomy due to cholecystitis with gallstones. Their serum lipid profiles and body mass index(BMI) were measured and compared with normal control persons. We adjusted the age and sex distribution in normal control group to the patient group. Results: Among 165 cases, the prevalences of whitish yellow stones, brown pigmented stones and dark pigmented stones were '21.2%, 60% and 18.2%, respectively. In the patients group, the mean age was 53.7+11.5 years and the ratio of male to fema]e was 1:1.6. BMI was significantly higher in the patient group(24.7+ 7.5kg/m )as compared to normal control group(21.9 ' 5.6kg/m, p<0.005). No differences were observed in the serum level of total cholesterol, triglyceride(TG), HDL-C, low density lipoprotein cholesterol(LDL-C), and the ratio of HDL-C to total cholesterol between the patient and control group. However, tbe old aged group, more than 50 years showed that the serum level of HDL-C, HDL-C/total cholesterol were significantly higher than in the group of normal population(48.3+ 18.0mg/dL, 0.30+0.12) than in tbe patient group(43.4+13.3mg/dL, 0.26 "0.09, p<0.005), and obese persons(BMI>25kg/m ) showed that their levels were significantly higher in the normal population group(53.0+9.5mg/dL, 0,30+0.08) than in the group of gallstone patients(43.3+ 1.7mg/dL, 0.24>0.07, p<0.005) also. Conclusions: Decreased serum level of HDL-C, HDL-C/total cholesterol might be a causative factor of gallstone formation in the obese or old aged group. (Korean J Gastroenterol 1996; 2S:683 - 6S9)