Quṭb al-Dīn Shīrāzī wrote several huge works not only on mathematical sciences and philosophy, but also on medicine: a commentary on volume 1 of Ibn Sīnā’s al-Qānūn fī al-Ṭibb entitled al-Tuḥfa al-Saʿdīya in nine volumes. This is not surprising because Quṭb al-Dīn came from a family of physicians and he received medical education in his youth by reading Ibn Sīnā’s Qānūn. This enormous commentary ought to give us comprehensive information about books on medicine and its allied disciplines available to Quṭb al-Dīn. In this article, I will elucidate how he utilized these books when composing such a huge work. Particularly, I will focus on how Quṭb al-Dīn used Ibn Rushd’s medical work in his al-Tuḥfa al-Saʿdīya, and rethink the importance of Ibn Rushd in the East.