Abstract: Objectives:To explore the generation，development and distribution of ant-i SARS （severe acute respiratory syndrome） specific antibodies in different populations；To search the improvement on the reagent kits.Methods:Serum collected from 3990volunteer blood donors before the outbreak of SARS were assayed.Meanwhile，397health care workers from SARS wards and 157cases of SARS patients were parallelly assayed by ELISA methods.Results:Ant-i SARS specific IgG antibody was found in 16 donors among 3990 volunteer blood donors.The positive rate was 0.40%.No specimen was positive with IgM antibody.Of 397health care workers，2 person had IgG antibody，and the positive rate was 0.5%.No IgM antibody was determinated in 397 health care workers.In 157 SARS cases，IgG antibody was found in 119patients.The positive rate became 75.79%.However，IgM antibody was found only in 68 SARS patients.The positive rate was 43.31%.Conclusion:The difference of IgG and IgM antibody positive rate were not significant between volunteer blood donors and health care workers from SARS wards（P=0.76＞0.05）.Certain positive rate exist when this kind of reagent kits were used to determinate IgG antibody ，which showed that the antigen coated on the micro-plate cross reacted with other kind of IgG antibody.It seems that the reagent kits need some improvement.