The objective of the research study was to determine the effect of the method for making bilberry preserves on the content of selected antioxidant compounds. The research material consisted of the products derived from bilberry fruits harvested in the forests in the Kuyavia and Pomerania Provinces. The preserves were made from fresh and frozen fruits according to the home cooking recipes. The following was analyzed: frozen fruits, low-sugar jam, syrup made “with heat”, syrup made “without heat” and two variants of bilberry soups. In the preserves, the following parameters were determined: total soluble solids, pH, total polyphenols, and anthocyanins. Of all the products analyzed, the thermally untreated syrup, i.e. the syrup made „without heat”, was characterized by the highest level of polyphenols and anthocyanins: 1.859 mg GAE/100 g and 549 mg/100 g, respectively. The addition of lemon juice to soup before cooking reduced the degradation of anthocyanins and their content (414 mg/100g) did not significantly differ (p ≤ 0.05 ) compared to the amount thereof in the soup made with frozen fruits (444 mg/100 g). As the time of thermal treatment was extended, the degradation of the compounds increased even to 80 % of the initial content of anthocyanins.