Polygala rausiana is described as a new species from the western Korinthia and eastern Achaia prefectures (nomoi) in the central northern Peloponnese. It is related to P. pruinosa and the recently described P. peshmenii, both Turkish taxa differing conspicuously by their indumentum type and carpological characters. The distinguishing characters are illustrated by SEM micrographs. P. rausiana occurs in an area with a remarkable number of rare endemic or otherwise notable species.