Abstract: Objective To analyze the incidence and characteristics of adverse events following immunization(AEFI) in Dongying city,Shandong province,and to evaluate the efficiency of AEFI surveillance system.Methods The data on cases of AEFI in Dongying city during 2008-2013 were collected from national AEFI surveillance system and analyzed with epidemiological description.Results Totally 682 cases of AEFI were reported by vaccination outpatient clinic during the 6 years period and over 70% of the cases were related to the vaccines included in the National Immunization Programme(NIP).Of all the AEFI cases related to the vaccines of NIP,69.94% were aged ≤ 1 year and the sex ratio of the cases was 1.34:1.91(male to female); 91.05% had common minor reactions and 8.5% had rare serious reactions; 4.84% had allergic skin rash and 0.73% had lymph node inflammations related to bacillus Calmette Guerin(BCG).Most of the cases(77.86%) had the adverse events within the first day after the vaccination,with an incidence rate of 34.49/100 000 doses.The top 3 vaccines involved in the AEFI cases were acellular pertussis-diphtheria-tetanus(APDT) vaccine(241 cases,53.57/100 000 doses),diphtheria-tetanus(DT) vaccine(52 cases,49.51/100 000 doses),and live-attenuated Japanese encephalitis(JE) vaccine(49 cases,18.77/100 000 doses).Almost all(672,98.53%)of the AEFI cases were completely cured and only 10(1.46%)cases had sequelae.Conclusion In Dongying municipality,the sensitivity and efficiency of AEFI surveillance system need to be improved and special attention should be paid to small children less than one year old,vaccinations of NIP vaccines and first dose,and the time period first day after the vaccination.