Endoscopic ultrasonography allows a high-resolution imaging of the pancreas and the extrahepatic biliary tract due to the high ultrasonic frequencies employed. This is of clinical benefit in the delineation of small pancreatic carcinomas complementary to ERCP and in the preoperative localization of endocrine tumors of potential pancreatic origin. Endosonography is the most accurate method presently available for the local staging of pancreatobiliary malignancy and thus helps avoiding diagnostic laparotomy for staging purposes. The role of endoscopic ultrasonography in the diagnosis of benign diseases such as chronic pancreatitis and choledocholithiasis has not yet fully been established. Endosonography, however, has no role in the differential diagnosis of benign and malignant disorders of the pancreas and biliary tract.