Endoscopic ultrasonography is an exciting new field, with a rapidly expanding literature describing a wide variety of applications. Despite remarkable advances in the field, a number of crucial issues remain to be resolved. These include the limited availability of educational programs for training, enormous initial start up costs for centers related to the cost of equipment and the lack of interchangeability with processors, paucity of outcomes research studies, and technical limitations of the currently available devices. The aim of this article is to review the basic principles, instrumentation, applications, and potential problems related to endoscopic ultrasound and to attempt to define the realistic role for this tool in contemporary medical practice.