Diagnoses, distribution and biology of twelve species of leeches from Namibia are given. Nine species belong to the family Glossiphoniidae and three to the family Hirudinidae. Five species, Alboglossiphonia cheili, A. conjugata, Batracobdelloides tricarinata, Placobdelloides multistriata and Hirudo michaelseni, are fairly widespread. The other species have a very limited distribution of which four species, Alboglossiphonia disjuncta, Helobdella conifera, Placobdelloides jaegerskioeldi and Asiaticobdella fenestrata, occur only in the northern half and three species, Oosthuizobdella garoui, O. stuhlmanni and Aliolimnatis obscura, occur only in the central part of the country. In addition three yet undescribed species were collected.