A list of ant species collected in eight calcareous grasslands in the Viroin valley (Viroinval, Belgium) is presented. Thirty species were identified, including Temnothorax albipennis, for the first time recorded in Belgium. Ant community composition and chorology of some ant species are discussed. Recommendations on how to use ant community composition and nest densities of several ant species to evaluate management in calcareous grasslands are given. It appears that in locations with encroachment of tall grasses (especially Brachypodium pinnatum) and spontaneous afforestation, due to a complete lack of or to inadequate management, most of the often rare xerophilic ant species are replaced by mesophilic, rather common species.