Abstract: Objective To investigate human enterovirus 71 (HEV 71) antibody levels and nature infectious status among children in Xi'ning city, 2009, and to provide scientific basis for prevention and control of hand, foot and mouth disease(HFMD).Methods Totally 181 serum specimens were colleted from 181 children of 1-6 years old in 2 counties of Xi'ning city, 2009.HEV 71 antibody was detected using neutra lization test and the results were analyzed with statistic methods.Results Sixty eight sera were positive for HEV 71 neutralizing antibody.The positive rate and geometric mean titers(GMT) were 37.6% and 1:16.12, respectively.The GMT and the positive rate were positively correlated with age with the lowest value among the children of 1 year old.There were significant differences in positive rate and GMT between age groups(X²=41.89, P<0.05; F=4.94, P<0.05).HEV 71 neutralizing antibody was negative among most of children of 1-6 years old in Xi'ning city.Conclusion It is important to take preventive measures to protect children of 1-6 years old, especially those under 3 years old, from HFMD.