A simple and sensitive method was developed for the quantification of free and conjugated bile acids in bezoar without prior hydrolysis. 3α-Hydroxy bile acids are first oxidized to 3-keto bile acids in the reaction catalyzed by 3α-hydroxysteroid dehydrogenase(3α-HSD). During this oxidative reaction, an equimolar quantity of nicotinamide adenine dinucleotide(NAD) is reduced to NADH and subsequently oxidized to NAD with concomitant reduction of nitrotetrazolium blue(NTB) to diformazan by the catalytic action of diaphorase. The diformazan has an absorbance maximum at 540 ㎚. The intensity of the color produced is directly proportional to bile acids concentration in the bezoar extracts. The optimum conditions for the enzymatic reaction such as effects of reaction time, reaction temperature and pH, and stability were investigated. Calibration plots for the sodium cholate observed to be linear and intra-, inter-assay analytical recovery of bile acids averaged 97.65±3.4%(S.D.). Therefore, it is considered that the quality control of total bile acids from bezoar or bezoar-containing liquid preparation using this simple and sensitive assay system will be acceptable. Also current bezoars and bezoar-containing liquid preparations were examined their total bile acids from this method.