Optimal treatment of gastric carcinoma requires accurate staging as there are marked differences in the prognosis of early and advanced gastric cancer which influence the decision for surgical resection versus nonsurgical palliation. Endoscopic ultrasonography (EUS), by virtue of its considerable accuracy, has become the method of choice for regional staging of gastric cancer. EUS is unique in its ability to image the gastric wall as a 5-layer structure that correlates with actual histological layers. Thus, tumor depth can be imaged very precisely. Peritumor inflammation is the most common cause for overstaging by EUS; difficulty in determining tumor involvement of, but not through, the subserosa is another important reason for inaccurate staging. EUS is able also to detect small lymph nodes in the perigastric region. Although assessment of malignancy in nodes can be difficult, ultrasound-guided fine needle aspiration cytology appears to be an accurate method to determine lymph node status. Surgery remains the standard treatment for gastric cancer, but new methods of endoscopic resection combined with high-frequency ultrasound may hold promise for future treatment of early gastric cancer. In addition to current radial and sector scanning instruments, recently introduced high-frequency ultrasound probes enhance the diagnostic possibilities of this technology.