Onosma atila-ocakii sp. nova [Boraginaceae, Sect. Asterotricha (Boiss.) Gurke] is described and illustrated as a new species. It grows in a steppe on magnesite rocks in EskiAYehir province (Central Anatolia, Turkey). Its description, photographs, and an identification key including related species (O. roussaei DC. and O. aucheriana DC.) are given. Diagnostic morphological and palynological characters of closely related species are compared and discussed. The characteristic features of indumentum and pollen structure are studied using a light microscope. The new species distinctly differs from related species because of its setose and adpressed retrorse-pilose indumentum, 2-3 rows of setules on foliar tubercles, 10-14 mm white petals and 2.1-2.6 x 1.7-2 mm dark brown nutlets. The International Union for Conservation of Nature threat category and observations on the ecology of the populations are noted. The distribution map of this new species and closely related species in Turkey is presented.