The Quaternary dispersal of the red fox Vulpes vulpes in the Mediterranean area was evaluated through the study of allelic variation at 45 enzyme loci in 120 individuals from 10 sampling sites. A 375 bp fragment of the mitochondrial cytochrome b gene was also sequenced in a total of 41 specimens from the same sampling locations. Nine allozyme loci were polymorphic. The proportion of polymorphic loci per population (P) ranged from 0 to 15.6%, and expected average heterozygosity (H) from 0 to 4.4%. A total of 18 different Cyt b haplotypes were detected. Most of them were confined to only one population. Both allozyme and mtDNA data implied that our fox populations were genetically fairly isolated from one another, suggesting low gene flow between them. This isolation should be of comparatively recent origin according to the slight differentiation among Cyt b haplotypes. Fox populations appeared to belong to two genetically distinct groups. With a mean value of Nei's D = 0.024, genetic distance between these groups was similar to that detected at subspecies level in taxa of large mammals. This pattern may have originated from different colonization waves during Quaternary glaciations and deglaciations. Red foxes from Sardinia were more closely related to the Bulgarian foxes than to the Iberian ones. However, repeated introductions to Sardinia probably also occurred from Central Italy and Spain, as suggested by the presence of haplotype A and a typical Central Italian allele, Ck-290.