The frequencies of 19 classical genetic markers for a total of 54 alleles were studied in a sample of 1,164 individuals born and residing in five different regions of Corsica. The results, which are also discussed in the context of the Mediterranean populations, show the existence within Corsica of a certain genetic differentiation between north and south which follows the linguistic subdivision differentiation. Compared to the other Mediterranean populations, Corsica also appears to be greatly differentiated from the populations of regions such as France and Tuscany, regions which have had great political and cultural influence. The Mediterranean population most comparable to Corsica is Sardinia. Despite their common origin, however, they do not prove to be absolutely identical. The genetic characteristics of Corsica and their relationship with the Mediterranean populations are interpreted in terms of demographic and matrimonial structure, isolation, and genetic drift. Am. J. Hum. Biol. 15:151–163, 2003. © 2003 Wiley-Liss, Inc.