In this paper the author analyzes Persian onomastic material found in Herodotus’ Ἱστορίαι and in Xenophon’s Ἀνάβασις according to phonological changes made to the borrowing upon entering the Greek lexical corpus. The aim of this paper is to examine the collected corpus of Persian names found in the works of the two aforementioned authors, and to describe, based on this corpus, the phonological changes that took place during the adaptation of these names in Greek, with the help of etymologies given in the paper, in order to establish how the Greeks adapted names of Iranian origin into their language. The analysis is based on language in contact theories proposed by Weinreich, Haugen and Filipović. With this aim, the author has compiled a corpus of 268 anthroponyms, toponyms and ethnics derived from Iranian languages and found in the aforementioned Greek works. He then researched the etymology of these borrowings, which are presented as dictionary lemma in the paper. The lemmata are arranged according to phonological changes, which are divided into consonantal and vocalic changes. These phonological adaptations are summarized in the concluding part of the paper, an analysis of which establishes that, despite the fact that some Persian phonemes appear in the Greek phonological system, their reflex in Greek does not correspond to what was expected, that is, it is not equal to the original Old Persian form. At the end of the paper, an appendix has been included containing a catalogue of all names analyzed in this work.