Background: St. John’s wort (Hypericum perforatum L.) is a plant known and used since ancient times, but it has gained popularity in the past 20 years as a remedy effective in treating depression. Throughout the centuries St. John’s Wort has been used to treat digestive disorders, helminthiasis, injuries, consequences of trauma, fever, snake bites, mental disorders and other pathologies. It was very popular until the advent of synthetic drugs. The effects of St. John’s wort were “rediscovered” in the late 1970s – early 1980s by German doctors who ultimately approved St. John’s wort as a prescription drug to treat depression. Since the adverse effects of synthetic antidepressants limited the use and acceptance by many patients, in the last two decades there has been an increased demand to alternative treatment of depression with drugs from Hypericum perforatum L. that have a high efficiency, as compared to synthetic antidepressants, but produce smaller adverse effects, and a lower rate of abandonment of treatment by patients. In this article some other effects of St. John’s wort, including the effect of healing, antifungal, anti-inflammatory, antimycobacterial, antiviral etc are demonstrated. The most important active substance responsible for various pharmacological effects of St. John’s wort is hyperforin. Conclusions: Since hyperforin in its pure form is unstable, it is of great interest and importance to study the action of hyperforin extracted from flowers of St. John’s wort of local flora of the Republic of Moldova in the laboratory of Scientific Center of Drug Investigation of Nicolae Testemitsanu State University of Medicine and Pharmacy, which presents the diethylammonium salt of hyperforin (hyperforin-diethylammonium) and is characterized by a good stability: in dry form it keeps unchanged at least one year and a half.