According to the definition by the Functional Food Science in Europe (1999), food may be considered as functional only if it is proved, based on the results of the representative scientific researches, that it has a beneficial nutritional effect, adds to the improvement of health state and well-being, and/or reduces the risk of diseases. Additionally, its form has to be reminiscent of that of traditional food, and its quantities, consumed as part of everyday diet, should be sufficient to have all the beneficial effects as above. Oats and its products are rich in many bioactive ingredients, such as: water-soluble β-glucans, compounds showing antioxidant activity (tokols, avenanthramides, polyphenolic acids), polyunsaturated fatty acids, especially α-linoleic acid, and fitosterols (for example β-sitosterol, Δ5-avenasterol). Oat products have an individual hipocholesterolemic effect, and, if their amount included into the diet contains 3 g of β-glucans per day, they decrease the total cholesterol level by 2 %, and the LDL cholesterol level by almost 5 %. Furthermore, the oats products included into the diet enhance the control of glycaemia in persons with inadequate glucose tolerance and type 2 diabetes. A low glycemic index of oats products may have importance not only in preventing and treating disorders of carbohydrate metabolism, but, also, the obesity. Meals based on whole-grain oat products are characterized by a high nutritional value and a relatively low energy density, and, at the same time, they produce a long lasting feeling of satiety. Oat products, rich in watersoluble dietary fibre, may be, also, a significant element that supports a diet therapy for hypertension and a dietary prophylaxis of large intestine cancer.