AbstractCornelian cherry (Cornus mas L.) is a plant growing in Central and Eastern Europe. Its fruits are a rich source of anthocyanins, flavonoids and iridoids. Among the iridoids, loganic acid is the most prevalent. The study aimed to examine the relation between loganic acid content, antioxidant capacity and hypoglycaemic effect in vivo for three Polish cultivars of C. mas. All tested cultivars strongly inhibited α-glucosidase and had similar amounts of highly bioabsorbable loganic acid. The loganic acid content was similar for each cultivar tested, while the cultivars differed in content of flavonoids and anthocyanins. The highest antioxidant potential was observed in the fruits of cv. Szafer, and the highest α-glucosidase inhibitor was cv. P5. A statistical analysis has shown that hypoglycaemic properties are prevalently driven by anthocyanin content and the antioxidant capacity, especially ferric-reducing ability partially based on loganic acid.