Vaccinium uliginosum L. (commonly known as bog bilberry) and Vaccinium myrtillus L. (commonly known as bilberry) are species of the genus Vaccinium (family Ericaceae). The red-purple-blue coloration of blueberries is attributed largely to the anthocyanins found in bilberries. Anthocyanins, known for their potent biological activity as antioxidants, have a significant involvement in the prophylaxis of cancer or other diseases, including those of metabolic origin. Bilberry is the most important economically wild berry in Northern Europe, and it is also extensively used in juice and food production. A review of the latest literature was performed to assess the composition and biological activity of V. uliginosum and V. myrtillus. Clinical studies confirm the benefits of V. uliginosum and V. myrtillus supplementation as part of a healthy diet. Because of their antioxidant, anti-inflammatory, anti-cancer, and apoptosis-reducing activity, both bog bilberries and bilberries can be used interchangeably as a dietary supplement with anti-free radical actions in the prevention of cancer diseases and cataracts, or as a component of sunscreen preparations.