Echoendoscopy has been found useful to better define gastrointestinal tract tumors which may be suitable for endoscopic treatment. In benign tumors, echoendoscopy may be used to decrease the risk of hemorrhage or perforation before resection of large polyps or submucosal lesions. The most important indications for echoendoscopy, however, are in the field of GI oncology, and the method may lead to a better selection of superficial cancers without lymph node metastases. However, endoscopic ultrasound is still limited in differentiating mucosal from submucosal tumors and in the detection and interpretation of small lymph nodes. Technical improvements and careful interpretation of echoendoscopy will increase the number of patients cured by non-surgical procedures in the future.