The intra-generic relationships within the intriguing genus Petrorhagia are currently debated, as the genus is underrepresented in recent taxonomic studies. In this study, we investigate the relationships among the species of Petrorhagia sect. Petrorhagia subsect. Saxifragae occurring in Greece. Based on a combination of ordination methods and discriminant analyses of 36 macromorphological characters, five species are recognized in Greece. The analyses showed that all currently known species from Greece (P. fasciculata, P. graminea, P. phthiotica and P. saxifraga) represent distinct taxonomic entities. According to our results, two recently collected populations from SE Peloponnisos represent a fifth, new Petrorhagia species, which is first described and illustrated here as P. laconica. It is related to the widespread P. saxifraga and the Peloponnesian endemic P. graminea, but clearly distinct from both species by a combination of morphological characters, including indumentums, inflorescence, calyx, capsule and seed characters.