In 193 BC, by means of a letter/πρόσταγμα – found at Nehavend, ancient Laodikeia in Media – sent to Menedemos, in charge of Media, king Antiochos III established the official cult of his wife, queen Laodike, appointing notable eponymous high priestesses, chosen among the princesses of the reign. He ordered that the letter was to be published on several stelae in the most prominent places (copies have been actually found in the region of Kermanshah, Axon nr. 171, and at Dodurga, ancient Phrygia, Ma 2002, nr. 37). In Media Laodike, daughter of Antiochus III and Laodike, and wife of her brother Antiochos (the son) coregent, was appointed. The ordinance reaches epistates Apollodotos and the city of Laodikeia in Media in three months, attesting to rapidity and effectiveness of the diplomatic exchange between the king and his officials. Active political role of queen Laodike, known from her correspondence with the cities of Sardeis, Teos, Iasos, and probably also Colophon, is enhanced by this ordinance which is the only direct proof of the existence of the dynastic Seleukid cult. The date of the establishment, implied by the text, of a high eponymous priesthood of the living king and his ancestors remains controversial.