Propolis is a potential source of natural antioxidants such as phenolic acids and flavonoids. Its wide biological effects have been known and used since antiquity. In the modern world natural substances are sought which would be able to counteract the effects of antioxidative stress, which underlies many diseases, such as cancer, diabetes and atherosclerosis. This paper aims to present the antioxidative activity of phenolic acids and flavonoids present in Polish propolis and the relationship between their chemical structure and antioxidative activity influencing its medicinal properties. Data concerning the biological activity of propolis are summarized here, including its antibacterial, anti-inflammatory, anticarcinogenic, antiatherogenic, estrogenic effects, as well as AIDS- counteracting and reparative-regenerative function.