The annual surgical incidence rate of hydatid disease in central Tunisia varies from 11.1 to 30.1 per 100,000 population depending on the district. In order to obtain more comprehensive data, we conducted a serologic survey in the district with the highest rate, using hemagglutination-inhibition to test 480 workers from a state farm and 190 inhabitants of villages in the neighborhood. The overall prevalence rate was 1.3% (9/670). Echotomography revealed liver cysts in all cases and the diagnosis was confirmed in the eight subjects who underwent surgery. If these preliminary results are confirmed by further surveys, mass screening might be considered in high risk districts.