In the scope of the ratification of an international reference boundary for the Rupelian-Chattian transition, it is important to evaluate both stages in their original stratotype areas. In this study, quantitative analysis of benthic foraminifera of several boreholes in the historical Rupelian stratotype area enables recognition of biostratigraphic events in the upper Rupelian and the Chattian: we present a coherent biostratigraphic scheme for the Oligocene southern North Sea Basin. The Rupelian-Chattian interval is subdivided into eleven biozones, of which the lowermost four (interval I-IV) were defined by GRIMM & STEURBAUT (2001) and the overlying seven (interval V-XI) are newly defined herein. A correlation between the Oligocene benthic foraminiferal zonation scheme for the southern North Sea Basin and the adjacent areas is established. Finally, some potential problems for the future decision on an international reference boundary for the Rupelian-Chattian are discussed.