This preliminary study, the first in Tunisia devoted to the Achaete annelids of the Lebna dam, identified nine species of Hirudinea in the study station. These species fall into three distinct families: four belong to the Glossiphoniidae(Batracobdella algira, Placobdella nabeulensis, Theromyzon tessulatum and Alboglossiphonia hyalina), one to the Erpobdellidae(Erpobdella testacea) and two to the Hirudinidae(Hirudo troctina and Limnatis nilotica). Two other species of the Limnatis genus have not yet been identified and could represent new species.