The aim of this study is to examine the role of St. John’s wort (Hypericum perforatum L.), a medicinal and aromatic plant, in traditional Turkish medicine and to compare it with current practices. According to medical manuscripts written in Turkish in Anatolia, this plant has served as a remedy for many ailments and is mentioned in numerous works within the Ottoman medical literature. The research is based on major medical texts written in Old Anatolian Turkish and Ottoman Turkish in Anatolia, as well as modern pharmacy and contemporary folk medicine data. This study investigates the etymological origin of St. John’s wort and its place as a medicinal plant in traditional Turkish medicine, as mentioned in Turkish medical manuscripts such as Müntehâb-ı Şifa (14th century), Yâdigar (15th century), Alaim-i Cerrahin (16th century), Gâyetü’l Beyân fi tedbir-i Bedeni’l- İnsan (17th century), Nizâmü’l Edviye (17th century), Terceme-i Cedîde fî’l- Havâssi’l- Müfrede (late 17th century), Derviş Mehmet’in Dühn Terkipleri (18th century), and Fazlızâde Mehmed Çelebi’s Müfredât-ı Tıbbiyye (18th century). Thus, the conditions for which St. John’s wort is used, along with its methods of application, have been identified and compared with current practices.