Abstract: Sera sequentially collccted from 30 Mongolian jirds (Meriones unguitus) infectcd with Erugia malayi were examined for specific antibodies by ELISA using soluble malayan adult worm and microfilarial antigens (MAA and MFA). Anti MAA antibody was detected as carly as the 2nd wcek aftcr infcction, and the ami-MFA antibody, the 3rd week. Both antibodies went on a steady increase, and reached peak level at the 12th weck. Thereafter, the anti-MAA antibody, after showing a little decrease at the 16th wcck, kept up a moderate level, and the anti-MFA antibody fluctuated at a high level. The level of specific antibodies was higher in 11 patently infected jirds than that in 19 occultly infected ones. It is suggested that the patently infected jirds may be used as an animal model for assessing the specific antibody level in filariasis.