A description is given of the Carboniferous ostracods from the borings in North-western Poland. Thirty-four species, including fifteen species and two subspecies considered as new ones, are described and their stratigraphic importance discussed. In the sediments under study, three horizons have been distinguished differing in their ostracods. The first of them may correspond to the Tournaisian, the second to the Visean, while the third's age has been approximately determined as the Namurian.