Assyrian Vowel Dissimilation research-article Jacob Jan de Ridder Zeitschrift der Deutschen Morgenländischen Gesellschaft, Jahrgang 170 (2020), Ausgabe 2, Seite 265 - 278 One of the features of the Assyrian dialects, that sets it apart from Babylonian, is the preservation of /a/ in the first syllable of non-finite forms of the D-stem and Š-stem: PuRRuS ~ PaRRuS and šuPRuS ~ šaPRuS. In the Neo-Assyrian period, a similar sound change /u/ > /a/ took place, presumably when followed by stressed /u/ in the next syllable: qubūru > qabūru ‘grave’. This short study will review the Old Assyrian and Neo-Assyrian periods while reassessing the Middle Assyrian text corpus and presenting some new evidence for this type of vowel dissimilation in nominal forms not related to the D-stem and Š-stem.