Abstract: Specific antibodies in the sera of mice experimentally infected with A. duodenale or N. americanus and of hookworm-infected individuals were detected by ELISA using in-fective larva or adult worm antigens.The antibody in mouse model could be detected as early as 7 days after infection with A. duodenale and remained detectable for at least 90 days, with a peak on the 15-30th day. But from 5-45 days after infection with N. americanus, antibody was dete-ctable at day 5 and only lasted 45 days with a peak on the l0th day. It is suggested that the pattern of antibody response may be useful for early diagnosis of hookworm infection and that it may be closely related to the duration of the larvae staying in the host tissues.Sera from 40 patients showed positive rates of 87.5 and 62.5% respectively with adult and larval antigens of A. duodenale. ELISA might be useful immunodiagnostic method for hookworm infection as well as a sero-epidemiological tool for mass examina-tion of ancylostomiasis.