Serologic tests for amebiasis, utilizing antigens prepared from Entamoeba histolytica HK-9, axenic culture in Diamond's media, have demonstrated reproducible results with good clinical correlation. The indirect hemagglutination test was positive in 100 per cent of all cases with hepatic abscess, in 99 per cent of cases of amebic dysentery and in 60 per cent of asymptomatic carriers. A population of uninfected subjects yielded less than 1 per cent of individuals with demonstrable amebic antibodies. Similarly, the complement fixation test was 100 per cent positive for the liver abscess, 91 per cent positive for patients with amebic dysentery, 23 per cent positive for asymptomatic carriers, and 0 per cent positive for the uninfected control group. The antibody responses to amebic antigens are discussed.