The objective of the study was to determine changes in the antioxidant properties and content of polyphenols, which occured during the ensuing phases of making juices and semi-concentrates from two cultivars of highbush blueberry cultivars (Vaccinium corymbosum L., cv. Earlyblue, Bluecrop). On the basis of the results obtained, it was stated that fruits of the two highbush cultivars of blueberries showed a high antioxidant activity the level of which was as follows: Earlyblue cultivar – 30.9 μM Trolox equivalents per g fresh weight; Bluecrop cultivar -41.2 μM of Trolox equivalents per g fresh weight. Losses in the total antioxidant capacity of raw juices with regard to fruits used were 55%, whereas the pomaces produced were characterized by as much as 32% (Bluecrop) and 46% (Earlyblue) of the initial antioxidant activity of fruits. During individual phases of the initial processing of fruit pulp (crushing, maceration, and pressing), the antioxidant properties of products obtained were reduced if compared with the initial raw material used.