The Roman rhetor Marius Victorinus published his Commenta in Ciceronis Rhetorica in the middle of the 4th century A.D. His work represents the only completely preserved ancient commentary on Cicerös early rhetorical work De inventione, which was among the most important textbooks of rhetoric during Late Antiquity and the Middle Ages. The significance of the Commenta is manifested by its transmission with around 60 manuscripts. This is the first and completely new edition of the text since 150 years. The edition is based on a critical new reading of all the manuscripts including a previously unknown manuscript family which transmitted the correct text in many places.