Abstract: The spaceoccupying lesions of biliary tract is  the main cause of obstructive jaundice. Because of the special location of the biliary system, traditional imaging is difficult to diagnose. Endoscopic  ultrasonography (EUS) can effectively avoid the interference of abdominal fat and intestinal gas, and clearly show the biliary system. In  recent years, EUS  guided fine needle aspiration and contrastenhanced endoscopic ultrasonography  techniques have high diagnostic value in the  spaceoccupying lesions of biliary tract  and play an important role in the differential diagnosis of biliary tract diseases.

Key words: endosonography, biopsy, , needle, cholangiocarcinoma, bile duct stones