Monoclonal antibodies (MAbs) directed against pathogen-specific epitopes of the galactose adhesin of Entamoeba histolytica were used in an ELISA to detect antigen from pathogenic E. histolytica. Single stool specimens from 74 patients in Bangladesh were used. The ELISA for pathogenic E. histolytica was positive in all 12 stool specimens with pathogenic amebae subsequently cultured, in no stool specimens with nonpathogenic E. histolytica and in 2 of 40 stools with other or no intestinal parasites detected. Specificity and sensitivity of the assay for pathogenic E. histolytica were 97% and 100%, respectively. These preliminary data offer promise for an ELISA using MAbs to the galactose adhesin as a rapid and sensitive means to detect the presence of pathogenic E. histolytica infection in stool specimens.