The genus Hypericum (Hypericaceae) is represented by nearly 100 taxa grouped under 19 sections in Turkey. Among them, 45 species are endemic. All members of the genus may be referred to as St. John's wort in the world. The genus is known as “sari kantaron, kantaron, binbirdelik otu, mayasil otu” and most of them, especially H. perforatum, have been used for the treatment of burns, wounds, haemorroids, diarrhorea and ulcers in Turkish traditional medicine. The pharmacological studies showed that this species has several activities: anti-depressant, anti-inflammatory, anti-microbial, anti-viral, anti-nociceptive and wound healing. The chemical composition of the Hypericum species is composed of naphthodianthrones (especially hypericin and pseudohypericin), acylphloroglucinol derivatives (especially hyperforin and adhyperforin), flavonoids (especially quercetin, quercitrin, hyperoside and biapigenin), tannins and volatile oils. Investigations on the chemical composition and biological activities, as well as hypericin content of Turkish Hypericum species, have been carried out for about 25 years. The aim of this study was to review and summarise important studies about Turkish Hypericumspecies. Endemic species are indicated with (e) in the text. Key words: Hypericum species, Turkey, endemic, chemical composition, biological activity, agricultural study, traditional use.