Background:With the publication of Sepsis-3 definition,epidemiological data based on Sepsis-3 definition from middle-income countries including China are scarce,which prohibits understanding of the disease burden of this newly defined syndrome in these settings.The purpose of this study was to describe incidence and outcome of Sepsis-3 in Yuetan sub-district of Beijing and to estimate the incidence rate of Sepsis-3 in China.Methods:The medical records of all adult residents hospitalized from July 1,2012 to June 30,2014 in Yuetan sub-district of Beijing were reviewed.Patients with sepsis-3 and severe sepsis/septic shock were identified.The incidence rates and mortality rate of sepsis-3 and sepsis/septic shock were calculated,incidence rates and in-hospital mortality rates were normalized to the population distribution in the 2010 National Census.Population incidence rate and case fatality rate between sexes were compared with the Z test,as the data conformed to Poisson distribution.Results:Of the 21,191 hospitalized patients,935 patients were diagnosed with Sepsis-3,and 498 cases met severe sepsis/septic shock criteria.The crude annual incidence rate of Sepsis-3 in Yuetan sub-district was 363 cases per 100,000 population,corresponding to standardized incidence rates of 236 cases per 100,000 population per year,respectively.The overall case fatality rate of Sepsis-3 was 32.0％,the crude population mortality rates of Sepsis-3 was 116 cases per 100,000 population per year,the standardized mortality rate was 67 cases per 100,000 population per year,corresponding to a speculative extrapolation of 700,437 deaths in China.The incidence rate and mortality rate of Sepsis-3 were significandy higher in males,elderly people,and patients with more comorbidities.The 62.1％ of patients with Sepsis-3 had community-acquired infections,compared with 75.3 ％ of infected patients without Sepsis-3 (P ＜ 0.001).The most common infection in patients with Sepsis-3 was lower respiratory tract infection.When compared with patients with Sepsis-3,patients diagnosed as severe sepsis/septic shock were more likely to have higher case fatality rate (53.4％ vs.32.0％,P ＜ 0.001)Conclusions:This study found the standardized incidence rate of 236 cases per 100,000 person-year for Sepsis-3,which was more common in males and elderly population.This corresponded to about 2.5 million new cases of Sepsis-3 per year,resulting in more than 700,000 deaths in China.