Background and Objective: The staging of gastrointestinal cancer has an important role in the treatment of tumor. This study was done to determine the efficacy of endosonography method for determining the stage and deepth of esophagus and stomach cancers. Materials and Methods: In this descriptive study, endosonographic staging was performed in 23 patients (15 male and 8 female) with esophagus and stomach cancers, confirmed with pathologic findings in Taleghani hospital, Tehran, Iran during 2002-04. The results of surgical staging compared to preoperative endosonographic method. Results: Mean age of 23 patients was 57.2 years (43-72 years). 30% and 70% of the patients had esophageal and gastric cancers, respectively. The accuracy of endosonographic staging of esophagus and stomach cancers was 82%. The accuracy of diagnosis, positive and negative predictive value of cancers in assessment of the depth of the tumor by endosonography procedure were 79.4%, 69.6% and 84.9%, respectively. Conclusion: Endosonography is a precise method for evaluating depth and staging of tumor and lymph node involvement