mtDNA polymorphisms were studied in a sample of 90 individuals of the Sicilian population using six restriction enzymes: HpaI, BamHI, HaeII, MspI, AvaII and HincII. (1) Three new patterns, for MspI, AvaII and HincII, have been detected. (2) At least two different mutations were found to account for both the AvaII morph 3 and the AvaII morph 9 as in many other Caucasian groups so far examined. (3) Seventeen types were found; of these six are new. The frequency (54.5%) of type 1-2 (2.1.1.1.1.2) is lower than in the rest of Italy whereas those of type 6-2 (2.1.2.1.1.2) (10.0%) and type 18-2 (2.3.1.4.9*.2) (12.2%) lie at the upper level of the Italian range. The 18-derivative, type 57-2 (2.3.1.4.13*.2), which is consistently found in all Italian samples, is present also among Sicilians with an incidence of 2.2%. (4) Of particular interest is that the HpaI-3/AvaII-3 complex, which is unique to groups of African ancestry, was found in Sicily at a frequency of 4.4%. For the first time an estimate of the amount of gene flow from Blacks to the Sicilian gene pool could be obtained.