The authors publish a unique tetradrachm of Pontic royal coinage. The coin was issued by Mithridates V Euergetes, father of Mithridates Eupator, and Queen Laodice Epiphanes and Philadelphos, evidently, Mithridates V’s aunt. The coin was found in the North Caucasus (Krasnodar Region, Apsheronsky District) together with an Athenian «new style» tetradrachm, also published in the article. The new-found tetradrachm of royal issue sheds light on the circumstances of Mithridates Euergetes’ accession to power. The published coin reproduces the tetradrachm type of the coins issued by Mithridates IV Philopator Philadelphos together with Laodice Philadelphos. The reverse of the coin corresponds partly to the type of Mithridates IV’s posthumous stater and tetradrachm of widowed Laodice, who reigned in Pontos after the death of her brother and husband Mithridates IV. The Queen’s portrait, titles and epithets are kept on Eueregetes’ tetradrachm, which makes it possible to assume that the coin was issued ca. 155–149 BC, for in 149 BC Mithridates V, according to the sources, was the only ruler. Evidently, Mithridates began to reign under his aunt Laodice’s regency, because he could not succeed to his father Pharnaces I immediately, the throne having been seized by his uncle Mithridates IV and aunt Laodice.