The aim of the present study was to investigate predisposing factors that lead to the formation of gallstones. In a group of 70 patients (51 with gallstones and 19 without, 20 possible risk factors were studied: percent of ideal body weight, the presence of superoxide dismutase in erythrocytes and in serum, lipid peroxide in serum, total serum cholesterol (Ch), high-density lipoprotein (HDL)-cholesterol (Ch), low-density lipoprotein (LDL)-Ch, very low-density lipoprotein (VLDL)-Ch, serum triglyceride (TG), HDL-TG, LDL-TG, VLDL-TG, serum bile acids (lithocholic acid, deoxycholic acid, chenodeoxy cholic acid, ursodeoxy-cholic acid, and cholic acid) and serum apolipoproteins (apo A-1, apo B-100, and apo A-1/apo B-100). Levels of apo B-100 and serum insulin in patients with gallstones were strikingly higher, and superoxide dismutase in erythrocytes was significantly lower than in individuals with no gallstones. Apo A-1 and HDL-Ch were also higher and LDL-Ch was lower in the gallstone group, albeit non-significantly so (P > 0.05) by t-test. However, Apo A-1, HDL-Ch, and LDL-Ch showed remarkably good discriminatory power in stepwise discriminant analysis of the 20 factors. Bile lipid composition was also measured and the cholesterol saturation index was calculated, but no significant differences were seen between the two groups. The results demonstrate that serum lipid patterns differ to some extent in patients with and without gallstones. Lipid derangement may contribute to the development of gallstone disease.