Abstract:The usefulness and the problems of endoscopic ultrasonograpy (EUS) in the diagnosis of submucosal tumors (SMT) of the upper alimentary tract were evaluated in this study. EUS was carried out in 86 cases with SMT of the stomach. Tumors of 13 cases was confirmed histologically (leiomyoma in 7 cases, leiomyosarcoma in one, lipoma in 2, gastric cyst in one, aberrant pancreas in one and Schwannoma in one case). In only one out of 22 cases with SMT of the esophagus, the tumor was surgically resected and a pathological examination revealed leiomyomaEUS was useful in estimating the histological origin of SMT by observation of the relationship between the location of the tumor and each layer in the gastric or esophageal wall. However, it was imposible to differentiate leiomyoma from leiomyosarcoma in myogenic tumors through the echoic pattern of the tumor by EUS alone at the present time.EUS was also useful in distinguishing the cause of extragastric compression showing similar findings with SMT, which could not be clarified by X‐ray or endoscopic examination. In fact, organs compressing the stomach were easily clarified by EUS. It was decided that EUS should be performed in all cases whenever there is any doubt of SMT existing after an X‐ray or endoscopic examinat