This study extracts the diagnostic, constant and dominant species of Slovak vegetation types based on statistical analysis of phytosociological data stored in the national vegetation database. The affinities of vascular plant, bryophyte and lichen species to the major syntaxa (alliances and classes) were calculated using a statistically defined coefficient of fidelity. Additionally, the evaluation of vegetation units by the criteria of sharpness and uniqueness was created. These criteria allow us to identify well-delimited alliances and classes or to point out those, for which delimitation is problematic and which are more difficult to define by statistical principles. The syntaxonomical revision and delimitation of some units with low values of sharpness and uniqueness should be considered in the future.