Dinoflagellate cysts (dinocysts) are abundant in the Eocene of the North Sea and provide a high-resolution biostratigraphic zonation. Twelve species are erected to accommodate zonal markers that have not been previously described. These are <i>Areosphaeridium ebdonii, Areosphaeridium michoudii, Cerebrocysta magna, Diphyes brevispinum, Diphyes pseudoficusoides, Hystrichosphaeropsis costae, Hystrichostrogylon clausenii, Membranilarnacia compressa, Phthanoperidinium clithridium, Phthanoperidinium distinctum, Phthanoperidinium powellii and Phthanoperidinium regalis.</i>