39 Background: Endoscopic ultrasound (EUS) is a routine staging test performed in patients with gastric and GEJ cancers and is highly valuable in treatment planning. The reported accuracy varies from 40% to 90%. We aim to investigate the staging performance of EUS at our institution and hypothesize that EUS accuracy can be influenced by tumor location, histology, and patient ethnicity. Methods: We performed a retrospective analysis of patients diagnosed with gastric and GEJ cancer between January 2006 and June 2015 who had EUS proceeded directly by surgery. T and N staging by EUS were analyzed for their sensitivity, specificity, and positive (PPV) and negative predictive values using surgery as the gold standard. The following variables were evaluated: tumor histology (intestinal or diffuse type), location (GEJ, cardia, body, or antrum), and patient ethnicity (Asian versus non-Asian). Results: Over 46 patients who met the inclusion criteria, EUS had T and N accuracy of 47.8% and 58.7%, respectively (p <.05). EUS had high specificity (88%) but low sensitivity (38%) for N staging. In predicting T staging, EUS was most accurate when the tumor was located in the body (72%, n = 7) and least accurate in the cardia (33%, n = 6) with 46% (n = 13) in the GEJ and 45% (n = 20) in the antrum. EUS tended to upstage the T value when a tumor is located in the body or GEJ, and downstage it in the cardia or antrum. The PPV using EUS for T1, T2, T3, and T4 were 89%, 22%, 45%, and 57%, respectively. The PPV using EUS for N staging was 73%. EUS was more accurate for T in Asians (55%, n = 33) than in non-Asians (31%, n = 13), and in intestinal type (56%) than diffuse (36%). For N staging, it was most accurate in the body (86%) and least accurate in the GEJ (50%). It was also more accurate in diffuse tumors (79%) than intestinal (52%) and more accurate in non-Asians (77%) than in Asians (53%). Conclusions: EUS as a common tool in preoperative staging may be inaccurate when performed in community hospitals. The predictive rate appears to vary in Asian vs non-Asian patients and in intestinal vs diffuse tumors. It is most predictive when the tumor is T1 and located in the gastric body. A prospective study is needed to confirm these findings.