The Albanian ethnic minority of the Cosenza province (Calabria, Southern Italy) is constituted by a population of 42,305 inhabitants living in 19 communes. The first presence of this population, in Southern Italy, dates back to the fifteenth century as a result of different immigrations. We have studied the G6PD in the population of this province by determining both the frequency of the G6PD-deficiency and the type of Gd(-) alleles in samples from 19 communes. The overall frequency estimate turned out to be 0.0294 and those of the 8 highland communes and of the 11 communes located in the valleys were 0.0242 and 0.033 respectively. Both the frequencies and the ratio between the frequencies of the different Gd(-) alleles are significantly different with respect to a previous study carried out on the non-Albanian population of the same areas. The high endogamy rate found among the grandparents' and among the parents of the probands living in the Albanian community, shows that this community is to a large extent reproductively isolated from the neighbouring populations, thus accounting for these differences.