Ostracods of the superfamily Cytheracea from the Uppermost Cretaceous and Lowermost Tertiary of central and north Poland are studied. Of the 63 species and subspecies described, 23 species and 2 subspecies are new. One new genus, Pulaviella, is erected. The variability, ontogenetic development and sexual  dimorphism of the described species are analysed. The geographical and stratigraphical distribution of studied Ostracoda and their comparison with those of Foraminifera are discussed.