Infrared (IR) spectroscopy is a simple and fast method with no or minimal sample preparation for measurement of medical samples including bile juices. Nonetheless, these methods have rarely been studied for diagnosis of various hepatopancreatico-biliary (HPB) diseases. Quite recently, only one research on IR spectroscopic differentiation between benign and malignant bile duct strictures has been reported [28]. They analyzed raw bile juice samples as well as chloroform-extracted samples, and found that the absorbance related to phospholipids was less intense in malignant samples compared to that in benign samples.