Abstract: Objective To evaluate the post-marketing safety of routine inoculation of inactivated enterovirus type 71 (EV71) vaccine and to compare the differences in adverse event following immunization (AEFI) between proactive and passive monitoring.Methods A post-marketing safety assessment was conducted among 3 162 children having EV71 vaccine inoculation in Chaoyang district of Beijing between August and November 2016.Of the children,770 were under an active monitoring on AEFI via mobile application information platform and 2 392 under a passive monitoring via their parents' feedback report.Results In the active monitoring group,the overall incidence of AEFI of EV71 vaccine was 42.33% (326/770),with systemic reaction being the main AEFI and rare and very rare adverse reactions were not observed.Whereas,in the passive monitoring group,the overall incidence of AEFI EV71 vaccine was only 0.67% (16/2 392) and significantly lower than that of active monitoring group (χ²=51 274.285,P<0.001),with temporal reactions being the main AEFI.Conclusion The EV71 vaccine is of good safety.Proactive monitoring is more conducive for the collection of vaccine safety-related data and safety assessment of the vaccine.