This dissertation examines the way in which Renaissance Italian scholars (ca 1450-1600 CE) handled the vast canon of ancient Greek and medieval Islamicate literature on the sense of smell in order to build a solid and sophisticated theory of olfaction to be applied to the field of medicine. It begins by surveying the relevant theories on the sense of smell put forward by classical Greek and premodern Islamicate authors. Then, it traces the recovery of these theories in fifteenth- and sixteenth-century Italy. The dissertation then focuses on Renaissance Italian discussions on the sense of smell taking place in the fields of natural philosophy and medicine. Two appendixes complete the dissertation. The first one provides a transcription of MS Milan, Biblioteca Ambrosiana, S85 sup., transmitting an Italian vernacular version of Theophrastus’ De odoribus (On odors). The second one offers a transcription of MS Florence, BNCF, Magliabechiano XII. 10, transmitting a sixteenth-century Latin translation of Theophrastus’ De sensibus (On the senses). Neither of these texts has ever been edited before in any form. This dissertation demonstrates that in the period between 1450 and 1600, in Italy, scholars devoted special attention to the issue of smell because of the serious implications it presented for the field of medicine. Since medicine had come to be heavily smell-based at the time, scholars were interested in better understanding the dynamics of smell as a means to developing a more refined set of medical theories and practices. Both natural philosophers and physicians took part in this project, and their work was fostered by the availability of an unprecedented wealth of sources from the ancient Greek and medieval Islamicate world that focused on the sense of smell. These newly available texts laid the groundwork for innovative discussions and prompted Renaissance scholars to approach the problem of smell in a different way than they had before.