The purple saxifrages, Saxifraga sect. Porphyrion subsect. Oppositifoliae, comprise the closest relatives of the arctic-alpine model plant S. oppositifolia and have a centre of diversity in the central and southern European mountain ranges. A multitude of taxa has been described and taxonomic concepts vary among different treatments. Using amplified fragment length polymorphism (AFLP) fingerprinting we show that some taxa indeed form strongly supported genetic entities best recognized on the species level (S. biflora, S. blepharophylla, S. retusa, S. rudolphiana, S. speciosa), while others (S. murithiana, S. paradoxa) are not genetically divergent at all. Saxifraga oppositifolia s. s. is phylogenetically incoherent. Plastid DNA sequence data show very limited congruence with the predominantly nuclear-derived AFLPs. Several co-distributed taxa (S. biflora, S. blepharophylla, S. oppositifolia s. s., S. retusa) share the same set of haplotypes. In the widespread species S. oppositifolia and S. retusa, highly divergent haplotype lineages were discovered, which exhibit a geographic rather than taxonomic structure. Recent and ancient hybridization and/or lineage sorting are likely responsible for the strong incongruence between data derived from nuclear and plastid genomes. Hybridization, which is known to occur among almost all taxa of this group when growing in sympatry, seems, however, insufficient to break down species barriers.