Abstract: In 1984-1990 longitudinal or sectional serological surveillance on filariasis by ELISAwith Brugia malayi adult antigen was carried out in 6 villages,Yuhang County,ZhejiangProvince,where malayan filariasis had been under control.During that period the microfila-raemia rate of inhabitants had been declining continuously till nil,the positive rate andmean optical density (OD) value in ELISA for positive inhabitants concurrently declinedyear by year,especially for children under age of 10.By the 5th year after control boththe positive rate and mean OD value were close to those of healthy persons living in no-nendemic areas of filariasis,no positivity was found in children.In the meantime,ELISAwas used to detect serum antibodies in members of a family who were infected with ban-croftian filariasis and inhabitants living around them in 1990.Positive rate of ELISA was higher in these inhabitants (8.33%) than in healthy persons (2.53%),and positive oneswere detected from children under age of 10.The results suggest shat the detection of antifilarial antibody by using ELISA is an effective method for the surveillance of filariasis.