The objective of the paper was to determine the antioxidant activity of and the content of compounds impacting this activity, i.e. total polyphenols and anthocyanins, in jams obtained from highbush blueberry fruits. Furthermore, the investigations included the impact of storage conditions and storage duration on the content of compounds, showing antioxidant activity, in jams produced. The investigation included three types of jam produced from this fruit: low-sugar jam (e = 38%), low-sugar jam with concentrated apple juice added (e = 38%), and high sugar jam (e = 65%). Highbush blueberry jams produced were stored during a period of six months, at temperatures of 6° C and 22°C, under no light conditions. The analytical part of the study comprised the profile of the basic chemical composition of fruits and jams. Additionally, after the 2, 4, and 6 months of storing the products manufactured, the antioxidant activity with ABTS^•+ radicals, and the content of total polyphenols and anthocyanins in them were determined. The jams manufactured from highbush blueberry fruits were characterized by a high antioxidant activity ranging from 17,2 to 20,3 μM of Trolox/g of the product. During the technological process, there was a decrease in the contents of polyphenols and anthocyanins in the highbush blueberry jams. This fact impacted the antioxidant activity of the products investigated. The highest, almost 50% losses were found in the case of anthocyanins. When jams were stored during a six month period, their antioxidant activity was decreased by 33% to 66% depending on the type of jam and the storage temperature. The lowest drop in the anthocyanin dyes occurring during their storage was stated in the high sugar jams, and this fact could be attributed to the stabilizing activity and impact of higher concentrations of sugar.