Abstract: Objective To study the clinical characteristics and the influence of co-infection on prognosis of acute upper gastrointestinal bleeding(UGIB). Methods The clinical data of 260 elderly patients with acute UGIB were selected, and they were divided into infection group and non-infection group. Their clinical characteristics, etiology, treatment and prognosis were analyzed. At the same time, 170 patients with acute gastric mucosal lesions of 260 cases were divided into infected subgroup and non-infection subgroup, and receiver operating characteristic(ROC)curve was used to analyze the efficacy of laboratory indicators in predictingfatality rate. Results The incidence of shock, fibrinogen(FIB), white blood cell count(WBC), C-reactive protein(CRP)and procalcitonin(PCT)levels in the infection group were significantly higher than those in the non-infection group(P<0.05). However, there were no significant differences in fatality rate and other factors between the two groups(P>0.05). The mortality and shock rates of the infection subgroup were significantly higher than those of the non-infection subgroup, and activated partial thromboplastin time(APTT)and FIB levels were significantly higher than those of the non-infection subgroup(P<0.05). Among 260 elderly patients with acute UGIB, serum urea nitrogen was the only independent predictor associated with all-cause mortality, and was of great predictive value in the subgroups with acute gastric mucosal lesions. Conclusion The main etiology of acute UGIB in elderly patients in emergency department is acute gastric mucosal lesion, followed by tumor. Mortality and shock rates are higher in UGIB - patients with infection, and BUN level at admission is an independent predictor of all-cause mortality.