The National Integrity System (NIS) assessment approach provides a framework which anti-corruption organisations can use to analyse both the extent and causes of corruption in a given country as well as the effectiveness of national anti-corruption efforts. The sixteen assessed pillars in the Slovak National Integrity System could be divided into two groups based on their performance: strong or weak pillars. Such division allows us to cluster the pillars into two sets of institutions possessing, in some extent, common features. Indicators of integrity and accountability in practice are very low in majority of pillars. This shows, together with the lack of independence in practice, that implementation of existing rules and legal frameworks are the major downsides of the NIS in Slovakia.