Using mtDNA sequences and 12 microsatellite loci, we compare populations of Testudo graeca from Sardinia and North Africa. The observed pattern of almost no differentiation combined with reduced variation in the Sardinian population is consistent with introduction in prehistoric or historic times from what is now Tunisia and neighbouring Algeria. Furthermore, in the light of the recently published recommendation to eradicate the non-native T. graeca from Italy, we review recent studies on the archaeological and fossil record, on the phylogeography and population genetics of the three other chelonian species occurring in Sardinia (Emys orbicularis, T. hermanni, T. marginata). We conclude that the extant Sardinian populations of all four species are not native. However, they are and should be safeguarded under EC law (Council Regulation No 338/97 on the Protection of Species of Wild Fauna and Flora; Flora Fauna Habitat Directive: Appendix IV, Art. 12) because they serve as a back-up for the declining mainland populations. Moreover, these populations constitute an important part of the human-shaped natural heritage of the Mediterranean.