From the fourteenth century ownwards in medieval Anatolia and the Ottoman realm, classical Arabic medical and pharmaceutical texts were translated or adapted into the newly emerging literary language of Anatolian Turkish. Turcophone authors likewise composed original medical works both in Arabic and the Turkish vernacular, drawing largely on the vast corpus of Arabic works circulating throughout the Islamic world, such as the court physician Muḥammed b. Maḥmūd Şirvānī (d. ca. in between 841/1438 and 1451). Among Şirvānī’s works, which were largely composed for royal patrons, are two regimen of health (regimen sanitatis) guidebooks, a genre of medical literature popular in both the medieval Islamic and Christian worlds concerned with maintaining humoral balance for maximum health by adopting moderate habits and proper hygiene. Rooted in Greek humoral theory, these practical handbooks provide specific advice for keeping in check the six “non-naturals”: air, food and drink, exercise and rest, sleeping and waking, repletion and excretion, and the passions and emotions. While he composed his first regimen of health (the Yaʿqūbiyya) in Arabic for the Germiyanid ruler, Yaʿḳūb Beg (r. 1402-1429), Şirvānī rendered the second version in the Turkish vernacular (the Sulṭāniyye) for the Ottoman sultan, Meḥmed I (d. 1420). The Arabic version exists in a unique manuscript, indicating a limited reception and circulation, as opposed to the Turkish vernacular version which was subsequently copied well into the sixteenth century. This paper proposes to compare the Arabic version of Şirvānī’s regimen of health with the Turkish one in order to better understand the relation between the vernacularized text and its Arabic counterpart. It also will attempt to trace Şirvānī’s Arabic sources (possibly Maimonides’s Fī Tadbīr al-Ṣiḥḥah?) to better understand how he drew on well-established classical Arabic textual traditions. One may assume that, in attempting to gain Ottoman patronage, Şirvānī turned to Turkish in order to make his text more widely accessible. This paper thus pivots around the following question: in choosing to compose in the vernacular, how did Şirvānī’s goal of greater accessibility reshape the text; i.e., how did popularizing through vernacularizing change the structure, contents, emphasis and rhetoric of the text?