The Kisfennsik Nappe is the uppermost tectonic unit of the Bükk Mountains (NE Hungary). The nappe consists of slightly metamorphosed platform limestones with dolomites at the base, and intercalating metavolcanites. On the basis of lithological character and macrofossils (Megalodontidae and Gastropoda) of uncertain age, the Kisfennsik Limestone was considered to be Ladinian–Carnian or Norian. The earlier and the here published results of microfacies investigations and Foraminifera and Dasycladaceae assemblage prove a Carnian lagoonal depositional environment, for the greater part of the Kisfennsik Limestone. In an eastern site (Galya-tető) reef facies was determined. Metavolcanites show different petrographic characters: acidic pyroclastics, andesitic lavas and basic tuffs, amygdaloidal basalts are present. Acidic-transitional metavolcanites appear at different stratigraphic horizons, below and above the basic ones. Based on stratigraphic position and petrographic features, the basic ones can be correlated with the Carnian extensional magmatism of the Bükk area (Szinva Metabasalt Formation). Considering the lithological features (presence of Triassic volcanites) of the Kisfennsik Nappe, and the structural pattern of the larger area, its W-Carpathian Silicic Unit origin can be excluded. The above mentioned features support an intra-Bükkian origin.