Abstract: One hundred and twenty eight patients with cholelithiasis and 11 control normal subjects were analyzed for different patters of bile acids by thin-layer scanning method. The results revealed that the content of total bile acids in the bile of normal cholecyst and choledochus was 50.38 mg/ml and 22.15 mg/ml, respectively; while that in patients was decreased. Especially the conjugated bile acids. Furthermore, the content of conjugated bile acids was more significantly decreased in patients with pigment stones （PS） than that in patients with cholesterol stones （CS）. The glycine conjugated bile acids was also decreased, the ratio of G/T being declined. It is postulated, according to the results, that the formation of P8 might initially be due to low composition of protein in diet and/or the presence of hepatic disease, which results in the decrease of bile acids and changes of composition of bile and affects the resolving effects of UCB and MCB, and consequently the formation of stones.