The karyotype of Atyaephyra desmarestii, the European freshwater shrimp, from Louros River (NW Greece) was studied through the examination of metaphase chromosome spreads from the first zoeal stage larval tissues. A total of 42 mitotic metaphases were examined and the diploid chromosome number was determined to 2n  =  32. The karyotype consisted of 22 metacentric and 10 submetacentric chromosomes. Atyaephyra desmarestii karyotype is reported here for the first time providing a basis for further cytogenetic comparative study of the species populations.