Rhythms in the Upper Jurassic-Lower Cretaceous carbonate sequences expressed by lithological-, micropaleontological data in several Central Carpathian sections were interpreted as a record of orbitally induced climate fluctuations. The rhythmic changes of the bed thickness are associated with regular fluctuations in abundance of microplankton content. These lithological rhythms can be correlated with the excentricity Milankovich cycles (periodicities of 120 and 480 Ka); the calcareous microplankton assemblages alternate with radiolarian associations in successive rhythms of 200–300 Ka. The first (late Valanginian) episode of Early Cretaceous greenhouse conditions is recorded by a low frequence fluctuations of δ¹³C values in the Western Carpathian sections.