Abstract: This paper reports the results of indirect fluorescent antibody test(IFA) with frozen sections of adult Brugia malayi as antigen for detecting antibody in human filariasis.Sera and ear-lobe blood were collected from 125 cases with bancroftian microfilaremia. The positive rate of IFA was 99.2% for serum and 96.8% for PBS eluates of dry blood, and the GMRT for the two groups was 31.14 and 33.08 respectively, showing no statistically significam difference in either positive rate or antibody titre.Observation on cross reaction in 289 cases of various parasitoses comprising nematode and trematode infections as well as malaria revealed positive rates of 0-7.1%. In view of the fact that GMRT of all the 62 bancroftian filariasis cases dropped significantly 6 monThs after diethylcarbamazine (DEC) therapy, and that both IFA positive rates and antibody titres were extremely low in historical bancroftian and malayan microfilaremia cases who had been cured by DEC 9-10 years ago, it is reasonable ta consider that IFA can be used to evaluate therapeutic effect of antifilarial drugs and as an useful technique in epidemiological surveillance of filariasis.