About 3,000 specimens have been studied from the Chasmops Series in the Central Oslo Region (Oslo-Asker, Ringerike districts). The presenceof conodonts in the Ogygiocaris Shale (4a?3) is reported. A new genus, Eoplacognathus, and 13 new species are described. Similarities between the European (Scotland, Sweden, Central Oslo Region) Caradoc and the North American midcontinent Upper Ordovician conodont facies are discussed. A preliminary account of the stratigraphical succession of conodonts from the Central Oslo Region is given.