The contents of sugars in cowberry (Vaccinium vitis-idaea L.) fruits were investigated considering their ripening degree and growth conditions. It was revealed that fructose made up the biggest part of sugars in berries, while the content of glucose was somewhat less. The content of saccharose was significantly less than those of fructose and glucose. With the ripening of berries, the amount of fructose and glucose as well as the total amount of sugars increased about ten times. The total contents of sugars and their composition in over-ripe berries changed insignificantly. Differences in sugar contents of berries from different habitats were not big and significantly less than those between different years.
Keywords: cowberry, ripening degree, sugar accumulation, fructose, glucose, saccharose, berry, growth conditions.