Major problems with a wide array of imperfect tests for diagnosis of amebiasis severely limit the understanding of its magnitude and epidemiology. A greater hindrance is the varied, inconsistent application of existing methods in different areas of the world. The best estimates suggest that probably 480 million people were infected with Entamoeba histolytica and 36 million developed disabling colitis or extraintestinal abscesses in 1981. At least 40 thousand deaths are attributable to amebiasis, and on a global scale, amebiasis likely ranks third among parasitic causes of death, behind only malaria and schistosomiasis. Much remains to be learned of its frequency of occurrence and epidemiology as needed improved diagnostic tools are developed.