Abstract Recent studies have shown the presence of a new endemic species of Soricidae, Crocidura sicula, in the Mediterranean area. Its karyotype consists of 36 chromosomes (NF = 56, NFa = 52) as previously recorded in specimens from Sicily and Gozo (Malta). Karyological analysis carried out in the present study on specimens from Marettimo (Egadi) and Ustica and on two additional Sicilian localities proved the presence of the same C. sicula karyotype. The multivariate analysis of skull and mandible of these populations revealed a pattern of geographic variation which is mainly related to a size decrease (76% of the total variability accounted for) in shrews living in the small islands around Sicily. The body biometrics of these insular shrews follows this trend, with some exceptions such as in Ustica, where shrews are relatively bigger. The shrews from Ustica show also melanic fur, which is darker than the grey-witheish colour found in conspecific populations. Such a phenotype could be the result of adaptation to the volcanic environment on this island. This latter population is, of all the small islands, the most divergent and differentiated from the mother-island; if considering its skull morphometrics (i.e. the residual 24% of total variability) and its body biometrics.