Amebopore was purified from axenically grown trophozoites of the Entamoeba histolytica strain HM1:IMSS. The purification procedure involved Mono Q anion-exchange chromatography and electroelution. Sequence analysis of the final product revealed that amebopore A was completely pure. Polyclonal antibodies against the purified amebopore were obtained from rabbits, and Western blot studies demonstrated their specificity. Sections of experimental, acute (1, 2, 3, and 4 days), amebic liver abscesses produced in hamsters were stained with the anti-amebopore antibody; in all the analyzed stages, amebopore appeared as a constitutively expressed cytoplasmic molecule in trophozoites. No extracellular or hepatocyte-membrane amebopore was found. This study is the first to trace amebopore in an in vivo model of amebic liver abscesses.