Twenty five samples accurately correlated to ammonite zones from the Early Bajocian to Early Bathonian oi the Bajocian stratotype have been studied palynologically. This article provides the first published account on the dinoflagellate cyst assemblages of the Bajocian stratotype. The systematic part gives an inventory of the 74 taxa of dinoflagellate cysts which have been encountered. The excellent preservation oi the material allowed detailed observations, in transmitted light and in SEM, on the morphology of numerous dinoflagellate cyst species. The observed stratigraphical ranges are documented and compared to published data from England, Scotland and Germany. In the middle part of the Bajocian, in the Humphriesianum and Niortense zones, a considerable increase of gonyaulacacean dinoflagellate cysts is observed. One species, Escharisphaeridia laevigata SMELROR 1988, is transferred to the genus Batiacasphaera DRUGG 1970. The genus Gongylodinium FENTON et al. 1980, and the type species Gongylodinium erymnoteichos FENTON et al. 1980, are emended.