Endoscopic ultrasound (EUS) is one of the most significant advances in the history of gastrointestinal endoscopy. It is unsurpassed in local and regional staging of cancer of the esophagus, stomach, pancreas, and rectum. Recently, EUS has been applied to a number of benign conditions such as achalasia, difficult-to-diagnose gallbladder disease, and submucosal tumors. As EUS gains in popularity and increased clinical application in the United States, it is imperative that gastroenterology nurses and associates be aware of this ground-breaking technology and its indications.