This contribution analyses the results of international sociological surveys that collected data in Slovakia, namely three waves of the European Values Study (EVS 1991, 1999, 2008) and two waves of the International Social Survey Programme (ISSP 1999 and ISSP 2006-2008). Focusing on the survey data the essay elucidates the concrete process of religious dynamics in post-communist Slovakia. Attention is paid to the so-called 'core of believers' as the main representative of 'traditional' religiosity, using this unique opportunity to explore the dynamics of this group within the last two decades. The author concludes that even if institutional religiosity is still far more dominant in the Slovak religious scene, the prevailing form of religiosity is of a post-traditional character.