Old Persian and Avestan are two intertwined branches from a collection of ancient Persian languages, the remains of which have been accessible to us. One of the features of these languages is their nominal declension. Each declined case of a noun, adjective and pronoun has its specific grammatical function, and meaning, determination of which is great importance to the understanding of the language. Pre- and postpositions acting on the case¬forms also play their own roles; roles that become more and more salient as the language develops into an analytic structure. The subject of this essay is the "Accusative", which -occupying the second rank after the "Nominative"¬is the most common case-form in the language of the cuneiform inscriptions of the Achaemenian kings.