Biological invasions have become a major cause of biodiversity loss. Tracing the origin of the populations of alien species is essential to infer the dispersal pathway and finally to set conservation policies aimed at preventing new introductions. The Italian wall lizard, Podarcis sicula, is one of the reptile species most widely introduced, with allochthonous populations occurring from the United States to Turkey. For some of them, instances of geographic expansion and competition/hybridization with autochthonous Podarcis sp. have been indicated. In the Iberian Peninsula, four introduced populations are known: Lisbon (W Portugal), Noja, Cantabria (N Spain), La Rioja (N Spain) and Almería (S Spain) while the species now widely ranges Menorca Island in the Balearics. Here we assess the origin of all five populations by comparing in a phylogenetic framework the cytochrome b gene sequences of specimens from the introduced and native populations. The results from this study provide evidence for distinct sources, pathways, and timing of introduction in Iberian Peninsula and Balearics by P. sicula from Tuscany, Calabria, Sicily, and Sardinia. This finding underpins the fact that P. sicula holds considerable potential invasiveness and advises for conservation strategies based on a global and preventive plan for avoiding new introductions as well as on eradication and control measures when prevention fails.