Abstract: Objective To investigate the incidence of gastrointestinal stress and conduct endoscopic mucosal evaluation to servicemen deployed in high-altitude areas. Methods In January 2018,a total of 614 servicemen were drawn from troops deployed in the area of Golmud (377 cases at the average altitude of 3 000 m) and Yushu (237 cases at the average altitude of 4 200 m).The epidemiological investigation was conducted by self-made questionnaire about gastroenterological symptoms.The serum helicobacter pylori (Hp) antibody and fecal occult blood were detected in these cohorts.The correlation between gastrointestinal symptoms,Hp infection and fecal occult blood was analyzed,and portable integrated digestive endoscopy was performed on soldiers with gastrointestinal stress to evaluate the mucosa changes. Results The incidence of gastrointestinal stress was as high as 50.8% (312/614),including diarrhea (38.4%,236/614),anorexia (35%,215/614),abdominal distension (27.9%,171/614),abdominal pain (17.6%,108/614),halitosis (17.6%,108/614),and hematemesis (7.3%,45/614).The incidences of diarrhea (44.6% vs 28.7%),ozostomia (21.5% vs 11.4%) and hematemesis/bleeding (9.3% vs 4.2%) in Golmud troops were significantly higher than those in Yushu (P<0.05,respectively).The average infection rate of Hp was 49.8% (360/614),with 49.3% (186/377) in Golmud and 50.6% (120/237) in Yushu,respectively,but no statistically significant difference was found between them.The detection rate of fecal occult blood was 24.9% (153/614),with 15.4% (58/377) in Golmud and 40.1% (95/237) in Yushu,showing a significant difference (P<0.001).Moreover,212 soldiers suffered with gastrointestinal stress symptoms received gastroscopy examination,and we found that all soldiers had different degrees of gastroesophageal and duodenal inflammations,including gastritis,ulcer,mucosal erosion and bleeding. Conclusion The incidence of gastrointestinal stress in troops deployed in high-altitude is high,such as diarrhea,abdominal distension,abdominal pain and constipation.We should positively explore and establish more effective methods to detect,prevent and manage the gastrointestinal health of soldiers.