Objective To understand the pathogenic epidemiological status quo among populations with respiratory tract infectious in Nanjing area.Methods The IgM antibody detection reagent kit against 9 kinds of respiratory tract pathogen was used to conduct the IgM antibody detection in 25 057 patients with respiratory tract infection in the Affiliated Nanjing Hospital of Nanjing Medical University,Affiliated Children's Hospital of Nanjing Medical University and Nanjing General Hospital of Nanjing Military Region from May 2013 to April 2015.Results A total of 8 575 cases(34.22％) of pathogen positive were detected out,in which Pneumonia mycoplasma (MP) antibody had the highest positive rate (23.77％);followed by respiratory syncytial virus (RSV,5.19 ％),adenovirus (ADV,4.56 ％),Parainfluenza virus type 1,2 and 3 (PIVS,4.02 ％) and influenza B virus (INFB,2.28％).The seasonal distribution of RSV,ADV and PIVS was significant and had high onset in winter and spring,but low onset in summer and autumn.Infants and young children had maximal positive cases in preschool period,which were 5 274 cases;as a whole,MP IgM antibody positive rate was gradually decreased with the age increase.Conclusion MP is the main pathogen causing respiratory tract infections in Nanjing area,followed by RSV.The pathogenic infection has a correlation with the age group,moreover which demonstrates the seasonal epidemic trend.