The paper deals with the occurrence of a rich radiolarian microfauna in the limestones of the Luckovska Formation of the Manin Unit (Mt. Butkov, Strazovske vrchy Mts., Central Western Carpathians). 36 taxa of radiolarians and four new species — ? Acaeniotyle florea n. sp, Cyclastrum decorum n. sp, Orbiculiforma trispinosa n. sp. and Paronaella trifoliacea n. sp. have been identified in prospecting gallery St-02–38 m. The associations found represent the stratigraphical range of Uppermost Valanginian–Hauterivian. Findings of tintinnids and ammonites (Vasicek & Michalik 1986; Borza et al. 1987; Michalik et al. 1990) in this formation prove Barremian age. However, the calcareous microfauna and calcareous nannoplankton found in prospecting gallery St-02–38 m does not determine the exact age. The older age of radiolarian associations can be explained here either by intraclasts of underlying rocks (Michalik et al. 1990) or by the assignation of the part of the Luckovska Formation to Hauterivian in this prospecting gallery.