1315 school-boys of the Cosenza province (Calabria - southern Italy) were subtyped for the PGM1 locus. Three subsamples were examined, two from the Tyrrhenian and the Ionian coasts, respectively, and one from the internal part of this province. The PGM1*1S, PGM1*2S and PGM1*2F gene frequency estimates obtained for the population of the Ionian coast were significantly different from those of the tyrrhenian coast. Since the three subsamples were of similar size, estimates weighted also with the respective population sizes were calculated.