The Slavonian mountains are situated in the eastern continental part of the Republic of Croatia, on the border of the Pannonian and Illyrian floristic area. Most of the mountain range is built of silicate and sandstone rock, while parts consist of limestone and marlstone. A gradient from mesophyllous to xerophyllous grasslands appear according to specific habitats. Grasslands are an important object of the nature conservation interest, not only because of their high biodiversity but also because they are a habitat of many rare and endangered species. Since there has been no research in this syntaxonomic point of view, the aim of this study is to research the remnants of such grasslands in this area. Their syntaxonomic status, floristic and ecological features have been analyzed. A compilation of a dataset of 102 vegetation releves has been used, that was compared with ecologically similar vegetation types in the neighboring countries. The species composition was classified by the cluster analysis and gradients was explored using ordination methods. Comparison of syntaxa was carried out using Ellenberg's ecological indicator values. The results clarify the position of local associations classified in three orders (Arrhenatheretalia elatioris, Brometalia erecti, Festucetalia valesiace) in broader syntaxonomic frame. Due to specific macroecological conditions and human impact most of the grasslands show transitional features among mentioned orders and are characterized by a rich biodiversity with numerous endangered species. Due to change in traditional land use these grasslands are under constant pressure of succession which is leading to large scale losses of such habitats. Due to its location on the border of different climate influences great abundance and diversity of flora and vegetation is present in this area. The study has shown that many of grassland species are highly threatened by extinction because of the progressive succession occurring on a large scale area, thus an effective management of such habitats has to be planned.