Dianthus ucarii Hamzaoglu & Koc (Caryophyllaceae) is described as a new species to science based on material collected in Kirklareli Province in northwestern Turkey. The new taxon belongs to sect. Carthusiani (Boiss.) F.N. Williams and it is closely related to Dianthus pinifolius Sm., an Eastern Mediterranean element. A description, illustration, and identification key for the new species are given. In addition, D. ucarii and D. pinifolius are compared in terms of general morphology and molecular phylogeny.