BACKGROUND/AIMS: Endoscopic ultrasonography (EUS) is now accepted as an essential tool for the diagnosis and the therapy of various gastrointestinal diseases. With regard to the biliary system, its high diagnostic sensitivity and specificity were reported recently. We assessed the clinical usefulness of EUS for the diagnosis of diseases of the liver, biliary tree, gallbladder and distal common bile duct. METHODS: We sent questionnaires about the clinical usefulness of EUS to the doctors who requested EUS examination for 32 patients with suspected diseases of the liver, gallbladder and around extrahepatic biliary tree from Aug. 2001 to Aug. 2002. We evaluated the answers and clinical characteristics of the patients. RESULTS: Patients were 17 males and 15 females with mean age of 61.8 years old. All received abdominal computed tomography (CT) before EUS and some had abdominal ultrasonography (USG) or endoscopic retrograde cholangiopancreatography (ERCP). EUS was more accurate and informative than other imaging modalities and gave definite final diagnosis for 31.2%. In 40.6%, EUS was helpful as an additional diagnostic tool. CONCLUSIONS: EUS was useful in 71.8% of the cases for the diagnosis of diseases of the liver, biliary tree, gallbladder and around distal common bile duct. EUS can be used as an important adjunct to USG, CT and ERCP.