Although first performed more than 20 years ago, endoscopic ultrasonography (EUS) has only recently been used for interventional/therapeutic purposes. The recognition and application of this versatile procedure by gastroenterologists who perform endoscopy has reached an all-time high, and the demand for symposia and tutorials devoted to EUS rivals that of endoscopic retrograde cholangiopancreatography 20 to 25 years ago. EUS has become an established part of the endoscopic armamentarium for many gastroenterologists. Despite its proved clinical utility for staging gastrointestinal (and lung) cancers, and its use in delineating the nature of "submucosal" tumors of the gastrointestinal tract, EUS has continued to evolve. Within the past 10 years, the safety and efficacy of EUS as a means of guiding tissue acquisition via fine-needle aspiration has been demonstrated, increasing its utility in gastrointestinal oncology. Newer indications currently under clinical investigation include the use of EUS as a delivery mechanism for novel immune-based and viral-based "chemo" therapeutic agents for patients with pancreatic cancer. Finally, the role of EUS as a reliable method to guide therapy to control the often refractory abdominal pain in patients with pancreatic cancer and/or chronic pancreatitis is being verified in clinical trials. The following is a brief overview of the current state-of-the-art in interventional EUS.