Endoscopic ultrasound (EUS) plays a vital role in management of upper gastrointestinal disorders, particularly cancer of the esophagus, pancreas, stomach, lung (via transesophageal mediastinal staging), and bile duct. Endoscopic ultrasound has also been valuable in detection of early chronic pancreatitis (CP). In cancer of the esophagus, the primary role of EUS is to determine whether disease is localized (T1-2, N0) and appropriate for surgery, locally advanced (T3-4, N1, M1a) (which may benefit from chemoradiation with or without surgery), or metastatic. Pancreatic and bile duct cancers are more complex given the controversy over portal vein resection. In centers that resect tumors invading the portal venous system, the role of EUS is limited to tissue confirmation or identification of metastases to the liver or distant lymph nodes. In centers that do not resect the portal vein invasion, EUS plays an important role in local staging. In lung cancer, EUS is emerging as an accurate, nonsurgical alternative to staging the mediastinum through EUS fine-needle aspiration. Endoscopic ultrasound has an important role in diagnosing CP because of its high degree of sensitivity. This has also led to controversy over whether EUS can overdiagnose CP. For these reasons, we recommend the use of a high threshold for EUS and that CP be diagnosed in conjunction with other standard tests (endoscopic retrograde cholangiopancreatography, pancreatic function tests).