The University of Cagliari owns a copy of Simon Grynaeus’ edition of Aristophanes’ Comedies (Basileae 1532), the first print edition ever to contain all eleven ‘complete’ plays. The book belonged to the German Medicus Physicus and philologist Janus Cornarius (1500-1558), editor and translator of several Greek medical works (particularly by Hippocrates and Galen), who filled the pages with notes concerning his professional and literary interest: interpretation of scenes, indication of parallel passages, use of medical and technical language, philosophical topics and even two potential textual conjectures. This essay presents a catalogue of Cornarius’ annotations and a brief commentary.