The sheep is the most important domestic animal in the region East Adriatic. Since strict selection is not practiced, much of the genetic value depends on adaptation to the environment. Therefore, the main objective of this study was to identify genomic regions showing signals of a positive selection signature. Our analysis was based on 200 individuals (males and females) from eighth indigenous breeds (Istrian Sheep, Dalmatian Pramenka; Dubrovnik Ruda Sheep, Istrian and Pag Island sheep), all representing East Adriatic or the Balkan sheep cluster (by extension meaning) as a single metapopulation, using the Ovine Infinium® HD SNP BeadChip. Our analysis was limited to the X chromosome only (21,748 SNPs), as such specific studies are rarely performed.