Our investigation has been conducted on a set of 854 Venetic personal anthroponyms from the area corresponding to the today’s Veneto/Friuli and areas around, derived from the Corpus Inscriptionum Latinarum a continuously updated Latin inscription catalogue covering the Roman Empire period and its provinces. The Venetic anthroponyms appear deeply Latinised and the root of each Venetic personal anthroponym was identified by comparing it with corresponding lexemes in the present surviving Slavic languages. It results that the Venetic personal anthroponyms having sure Slavic roots in the set is 23.89% of the derived Venetic personal anthroponyms, which permits to estimate that during the Roman Empire period, i.e. about five cen., roughly about 24% of the Venetic population had Slavic ascendancies. This highlights that Slavs were already present in the today’s Veneto/Friuli and in said areas around well before the Roman Empire period and the VII century A.D. of the generally accepted theory of the Slavs late arrival in Europe. The logical consequence is that this theory is wrong and should be rejected.