Immune sera from 11 patients cured of amebic liver abscess was used to identify antigens of Entamoeba histolytica. Strain HM1-IMSS, among the most virulent in axenic culture, was used. The 37 and 90 Kd antigens were surface glycoproteins as indicated by lactoperoxidase iodination and by Concanavalin A blotting; the 59 Kd antigen was a mannose containing glycoprotein that did not appear to be on the cell surface. Western blots of 11 different immune sera revealed specific binding of immune IgG to 9 amebic proteins. Most frequently recognized proteins were of molecular weight 37, 59, and 90 Kd. The immunoblot pattern in 5 patients was unchanged for up to 30 months post-treatment for liver abscess.