Essential oils - aromatic plant substances with strong biological activity - are increasingly used in pharmaceutical and cosmetic production. An example of an extremely active essential oil is thyme essential oil, obtained by steam distillation of thyme herb. Thyme oil has proven antibacterial, antifungal, and antiviral activity. It is also characterized by strong antioxidant activity, as well as anti-inflammatory, antispasmodic, and repellent properties. The biological activity of thyme oil and its possible applications depend on the origin of the raw material and the extraction method. Thymol and carvacrol are mentioned as the most active compounds of thyme oil, although other ingredients are also mentioned. The intended therapeutic effects can be achieved by using pure, natural oil and proper application. In cosmetic production, thyme oil can act as an active ingredient of the product and/or a natural preservative that extends its shelf life.