In this paper the results of studies on the effects of oat products on total cholesterol and HDLcholesterol in plasma as well as on postprandial glycaemia were reviewed. After supplementation of diet with oat products, a decrease of plasma total cholesterol level and an increase in the ratio of HDLcholesterol to total cholesterol were observed. These effects were more pronounced in patients with hyperlipidemia than in patients without lipid metabolism disorders. After supplementation of test meals with oat products, a decrease in postprandial glycaemia was observed. Experiments on animals and clinical studies clearly demonstrated that water soluble components of dietary fiber – β-glucans are responsible for both hypocholesterolemic and hypoglycaemic effects of oat products. Therefore, the supplementation of a diet with oat products rich in β-glucans are recommended particulary for patients with hyperlipidemia or non-insulin dependent diabetes mellitus or both. Additionally, oat products rich in β-glucans, with low energy content (for example Oatrim) are recommended as additives to food products for patients with obesity.