This is a new text edition, based on several manuscripts not yet employed by previous editors, with Prolegomena, Italian translation, commentary and indices of the Ars Rhetorica ad C. Herennium. This text was long-time wrongly ascribed to Cicero as his own correction of De inventione, an analogous but incomplete handbook of rhetoric. The Prolegomena and the commentary represent the largest approach ever attempted to this important work of Latin literature.