Background: Superior mesenteric artery syndrome (SMAS) is a symptom complex condition that caused by the vascular compression of the third portion of the duodenum between the aorta and superior mesenteric artery. Diagnostic delay of SMAS is common because of lack of high index of clinical suspicion. The aim of present study was to assess whether the esophagogastroduodenoscopy (EGD) can give the useful clue for suspecting SMAS. Patients and Methods: From August 2002 to February 2013, we prospectively collected data on patients who underwent EGD and upper gastrointestinal (UGI) contrast study. The recruitment in present study was limited to patients who had that more than one of the EGD findings: 1) a vertical pulsatile compression and partial luminal opening less than one-third with aeration at least 10 seconds at the third part of the duodenum (partial opening of the duodenal third part with aeration), 2) a large amount of bile mixed fluid (bile lake) in the stomach, 3) the proximal duodenal dilatation from the pulsatile compression (proximal duodenal dilatation). Patients with more than one of these endoscopic findings underwent UGI contrast study to confirm SMAS. The patients were classified as 2 groups: SMAS group and non-SMAS group according to the result of UGI contrast study. Results: Of 29 enrolled patients, 18 patients had SMAS and 11 had no-SMAS. There were no significant differences in baseline demographics, clinical features, and growth status between the two groups. The three most common presenting symptoms were postprandial discomfort (61.1% in SMAS patients and 54.5% in non-SMAS patients), abdominal pain (55.6% in SMAS patients and 90.9% in non-SMAS patients), and early satiety (50.0% in SMAS patients and 18.2% in non-SMAS patients). EGD findings were observed in both groups as bellows: 1) partial duodenal third part opening with aeration (0 vs 9.1%, p=0.38), 2) partial duodenal third part opening with aeration and bile lake (5.6 vs 18.2%, p=0.54), 3) partial duodenal third part opening with aeration and proximal duodenal dilatation (22.2 vs 45.5%, p=0.11), 4) partial duodenal third part opening with aeration, bile lake and proximal duodenal dilatation (72.2 vs 27.3%, p=0.027) Conclusion: EGD is useful for early suspicion of SMAS in children.