Over the past two decades, endoscopic ultrasonography (EUS) has undergone a transition from being a novel imaging technique to a clinical diagnostic test that is necessary for the optimal management of gastrointestinal diseases. EUS has established itself as an important diagnostic modality, mainly for the detection and staging of gastrointestinal cancers. As EUS has become more widespread, research has gradually shifted towards studies that explore the effect of EUS on patient management and outcome. These outcome studies have examined the primary clinical applications of EUS, such as esophageal, gastric, pancreatic, and colorectal cancer staging, as well as the role of EUS in the diagnosis of inflammatory pancreatic diseases. Widespread use of EUS has recently led to studies that examine complications associated with the performance of the procedure. Endosonographers have continued efforts to define a clinical role for EUS in other gastrointestinal diseases, such as portal hypertension. EUS-guided fine-needle aspiration (FNA) is continuing to develop into a powerful diagnostic tool for the management of lung cancer and other mediastinal diseases. New applications for EUS-FNA are also emerging. Finally, investigators are continuing to explore the remaining frontier of EUS-guided therapy.