My project explains the origins and influence of Gariopontus of Salerno’s seven-book medical text, the Passionarius, which was produced ca. 1050 from late ancient sources, and which remained popular through the sixteenth century. My project offers the first critical edition of this text, which was published three times in the Renaissance. I include paleographical descriptions of all fifty-nine surviving manuscripts, as well as indices of glosses, technical terminology, and material medica.