Soluble antigens of adult worms (MAA) and microfilariae (MFA) were analysed by means of SDS-PAGE and enzyme-linked immunoblotting (ELIB). The adult worms and microfilariae were collected from abdominal cavity of Mongolian jirds infected with Brugia malayi. The results indicated that MFA shared 64-67 kDa and 56-58 kDa protein components with the peritoneal fluid of the normal jirds. Sera from normal jirds were found to recognize 60 kDa, 74 kDa and 100 kDa fractions of MFA, but did not recognize any bands of MAA. Sera from positive jirds which were infected with B. malayi for 6 months could recognize 42 kDa and 14.5 kDa of MAA, but sera from negative jirds could not. The results indicated that the 42 kDa and 14.5 kDa protein components of MAA might be specific diagnostic antigen fractions.