Up to now the data about the age of radiolarites of the Silica Nappe in the Slovak Karst has been established by Dumitrică (in Dumitrică & Mello 1982) as Callovian-Oxfordian in the locality Bohunovo. In the Drienovec Mt., at the locality of Bleskovy pramen near the village of Drnava radiolarites with Upper Bathonian-Lower Callovian radiolarian microfauna also occur as lithoclasts in carbonate breccia of debris flow deposit origin (Sykora & Ozvoldova 1996). Apart from this finding the presented paper brings the further information about the age of the radiolarite in this locality, based on the radiolarian research. The radiolarian assemblages represent the stratigraphical range – latest Bajocian-early Bathonian to upper Bathonian-early Callovian (Unitary Association Zones: U.A.Z. 5 - U.A.Z. 7 according to the biozonation of Baumgartner et al. 1995).