The ELISA [enzyme-linked immunosorbent assay] test for human hydatidosis applied to 289 sera yielded a positive reaction at 1.15 OD [optical density] without any cross reaction. It detected 42 cases of hepatic localizations, 5 of 5 pulmonary hydatidosis and 1 for 4 other localizations. A good correlation and complementarity was shown with other serological tests such as immunofluorescence and indirect hemagglutination. The ELISA test applied to post-therapeutic controls did not give a serological peak for 6 of 13 cases, and was negative between days 7-90 following treatment. Serological negativity does not necessarily imply cure.