St. John’s wort (Hypericum perforatum) has been traditionally used for centuries to treat various ailments. On Rujan Mountain, this plant was used in ethnomedicine (197 reports), ethnoveterinary (54 reports) and for other purposes (1 report). Out of the total of 130 respondents, 101 knew the use of St. John’s wort (78 Serbian, and 23 Albanian respondents). Respondents of Serbian nationality participated in greater numbers and gave more statements about the use of St. John’s wort. In ethnomedicine, St. John’s wort flowers were most often used (61.4%). The preparation of oil extract (58.9%) was the most used form. The external application was the most frequently used (62.4%). The treatment of skin burns was usually use (34%). In ethnoveterinary, the only application of St. John’s wort, according to the reports, was the use of oil extract form, prepared with the flowers for the external treatment of skin wounds in cows and goats. For other purposes, the respondents collected St. John’s wort in the field and sold it to buyers. New applications that have not been mentioned in previous research are the use of St. John’s wort for the treatment of colds, skin ulcers and in the prevention of health.