Herbal polyphenol compounds are intensively investigated due to their numerous and well-known beneficial effects on the human body. In this thesis, eleven samples of leaves of Vaccinium myrtillus were examined. The aim was to determine the antiradical activity of extracts, the ability to inhibit tyrosinase and the content of the two main groups of polyphenols: flavonoids and phenolic acids, which are considered to be the main carriers of these activities in plants. Furthermore, the presence of arbutin in the samples was tested. The content of total polyphenols, flavonoids and phenolic acids in samples was determined spectrophotometrically. The antiradical activity of the extracts was tested by DPPH free radical, while for tyrosinase inhibition the enzyme from mushrooms was used. The content of certain phenolic acids, flavonoids and arbutin was determined by HPLC analysis. In addition arbutin was analysed using TLC. Results have shown that the extracts differ in the content of the tested compounds, as well as in antiradical activity and inhibition of tyrosinase. Generally, all the samples were good free radical blockers, while the effect on tyrosinase inhibition was much weaker. HPLC analysis determined the presence of chlorogenic acid and hyperoside in all samples, while p-coumaric acid was found only in one sample, the same one that showed the highest inhibition of tyrosinase. Arbutin was detected in three samples, but in very small amounts.