The article presents the analysis of the PERV retrovirus subtypes A and C frequency in populations of Ukrainian and foreign breed pigs. Different frequencies of the PERV A/C genome presence in animals of the studied breeds were established. The largest relative number was observed in the group of wild pigs (86%), the smallest was in the groups of Poltava meat and Piétrain breeds. Animals free of both virus subtypes were found in all study groups. The article considers the hypothesis of an increase in the frequency of PERV retrovirus in the pigs’ genome during domestication. Its integration caused a gene mutation responsible for fat deposition which led to increased fat amount in carcasses and could be picked up by selection in the process of creating breeds. However, there is no obvious link between the spread of the virus in modern breeds in different areas of productivity. Also, there is no association between carcass fat amount and the presence of PERV in the genome. It is established that the information on the PERV A/C distribution in pig breeds hold in Ukraine is useful in terms of the possibility of using each of them for xenotransplantation. Also, this information can be used to justify the selection of founding breeds in order to create lines of pigs free from the endogenous retrovirus genome.