This study describes the new species Astragalus oksutdagensis (A. sect. Eustales) from Kayseri, Turkey. The species is compared morphologically to the two similar species A. flavescens and A. vestitus, considering also pollen micromorphology. The geographical distribution of A. oksutdagensis, A. vestitus and A. flavescens is mapped. The phylogenetic relationships between the new species and other closely related species in the genus are inferred based on DNA data from the internal transcribed spacer regions (ITS) and it is shown that A. sect. Eustales is monophyletic but closely related to A. sect. Tragacantha. The new species is assessed as critically endangered (CR) following the IUCN Red List Categories and Criteria.