A phytosociological study of the West Carpathian mesic hay meadows and pastures (order Arrhenatheretalia elatioris) was performed and is the first unified investigation into the vegetation diversity in the area, which is situated in three countries (Slovakia, Czech Republic and Poland). Because of the differences in the current classification systems used in different countries it was not possible to make a single selection of the Arrhenatheretalia relevés from the databases, so a data set containing relevés originally assigned to three orders encompassing this vegetation in hay meadows and pastures in the area (Arrhenatheretalia elatioris, Molinietalia and Nardetalia strictae) was established. This data set was classified using cluster analysis. Only the cluster corresponding to the order Arrhenatheretalia elatioris at the level of three clusters was further classified in the same way as the whole data set. The ecological interpretation of the classification was based on altitude, Ellenberg indicator values and geological bedrock. The clusters were also compared with the syntaxonomical assignment of the relevés by their authors. The classification at the level of 12 clusters reflected the most widespread vegetation types of mesicmeadows and pastures recorded in the area. The vegetation of extensive pastures, corresponding to the association Anthoxantho odorati-Agrostietum tenuis, seemed to be more similar in floristic composition to the mesic meadows of Arrhenatherion elatioris than to the intensive pastures of Cynosurion cristati, where it was traditionally classified, which has important conservation consequences because of the different position of these units in conservation systems such as Natura 2000. Higher altitude meadows were divided into four vegetation types including meadows corresponding to the association Gladiolo imbricati-Agrostietum capillaris, which is a frequent community in the Polish Carpathians that does not occur in the other regions. Montane meadows currently classified in Polygono bistortae-Trisetion flavescentis were less clearly distinguished, probably because of their patchy distribution in theWest Carpathians. The differences in vegetation diversity of meadows and pastures between particular countries were confirmed, with Gladiolo imbricati-Agrostietum capillaris occurring predominantly in the northern part of the West Carpathians and Anthoxantho odorati-Agrostietum tenuis virtually absent here. The ecological determinants of variation in montane meadows are discussed.