Abstract: Objective To investigate reported incidence of adverse events following immunization(AEFI) and to provide evidence for safe vaccination.Methods According to the "Nationall Requirements of Guidelines for Adverse Events Following Immunization-Pilot Study" and with passive surveillance or active surveillance,the AEFI cases were collected in Yuexiu district of Guangzhou city from 2006 to 2009 and analyzed.Results Totally 286 AEFI cases were reported from 2006 to 2009 by the surveillance system.The estimated incidence of AEFI was 12.12/100 000 dose vaccination and most of the AEFI were reported during March to August.The AEFI reports involved 21 kinds of vaccine.Among all AEFI reported,there were 134(5.67/100 000 doses) general response,87(3.68/100 000 doses) abnormal reaction,and 65(2.75/100 000 doses) coincidental reaction.The vaccines with first three frequent AEFI were Areinfluenza H1N1 influenza vaccine(75/100 000 doses),MR vaccine(67.11/100 000 doses) and DTwP vaccine(66.99/100 000 doses).The general reactions were fever(49.25%),local swelling and induration(29.1%),and fever with local swelling and induration(11.94%).The first three abnormal reactions were allergic skin rash,aseptic abscess,angioedema.The main coincidental reaction was upper respiratory infection.There were significant differences in the incidence of AEFI between vaccination with and without dilution(χ²=5.68,P=0.017),and between different injection way(χ²=4.7,P=0.03).The children with allergy history were more likely to have abnormal reaction than general response with an odds ratio of 2.1.Conclusion No vaccine quality problem and mistake vaccination were found in AEFI surveillance.The vaccines are used safely and the incidence of AEFI is within the expected range in Yuexiu district of Guangzhou city.