Abstract: Objective To analyze the incident characteristics of adverse event following immunization(AEFI) in Anshan city during 2009-2013 and to provide a basis for the improvement of AEFI surveillance.Methods The data on reported cases of AEFI were collected through the AEFI Information System of China and analyzed with descriptive epidemiological methods.Results During the period,totally 250 AEFI cases were reported in Anshan city,of which,232(92.80%) had common reaction,12(4.80%) had rare reaction,and 6(2.40%) had coincidental event,with the reported incidence rates of 8.78 per 100 000 doses for overall AEFI and 0.42 per 100 000 doses for rare vaccination reaction,respectively.Among all the AEFI cases,the male to female ratio was 1.36:1; 80.00% were aged 0 to 1 years; and the first three proportions of AEFI were related to vaccination of diphtheria-pertussis-tetanus vaccine(DPT),measles-rubella vaccine(MR),and diphtheria-tetanus vaccine(DT).The top three AEFI incidents reported were related to the vaccinations of MR,DT,and DTP and 84.40% of the incidents occurred within 1 day after the vaccinations.Of all the reported cases,97.20% were cured and only 6.00% were hospitalized for treatment.Conclusion AEFI often occurred within 1 day after the vaccination of vaccines covered by National Immunization Program of China and the most of the AEFI cases had common reaction among young children in Anshan city and the AEFI surveillance system in the city had good sensitivity.