There are three pairs of vowel phonemes in Parthian - long and short a, i, u, and two single long vowels e, o which appeared from ancient diphthongs. Consonant mutations included the following: *z, *d > z, *dv > b and some others. The grammar structure can be characterized by analytism: ancient categories of gender and case were lost in noun declension, final endings of verbs were replaced by analytic construction using the ancient participle in -ta-. However, in early inscriptions indirect cases and verb inflections can be somehow seen.
Parthian script was a descendant of Aramaic alphabets. The oldest documents found include the economic documents from Nisa (1st century BC). They are written in Parthian script with additions of ideograms, as well as rock inscriptions dating back to the 3rd century AD.