Introduction. The simple term of dietary fibre originating with Hipsley (1953), but the most consistent definition is: non-digestible carbohydrates and lignin, functional fibers consisting of  isolated, non-digestible carbohydrates which have beneficial effects in humans and total fibre as the sum of dietary and functional fibers.  Materials and methods. The profile literature and database were evaluated and analyzed. Results. Nowadays there are several classification systems of dietary fibers based on: role in the plant, type of polysaccharide, their simulated gastrointestinal solubility, products of digestion and physiological indicators. The accepted classifications are based on their solubility in a buffer at a defined pH, and/or their fermentability in an in vitro system. There are 2 groups of dietary fibers: water-insoluble/less fermented (cellulose, hemicellulose, lignin) and the water-soluble/well fermented fibers (pectin, gums, mucilages). Functions of dietary fibers in human body: add bulk to the diet; making feel full faster; attract water and turns to gel during digestion, trapping carbohydrates and slowing absorption of glucose; lower total and LDL cholesterol; regulate blood pressure; speed the passage of foods; add bulk to stool; balance intestinal pH and stimulate intestinal fermentation production of short-chain fatty acids. The benefits of dietary fibers on human health: may reduce appetite; lower variance in blood sugar levels; reduce risk of heart disease; reduce symptoms of metabolic syndrome and diabetes; reduce risk of colorectal cancers; alleviate constipation. The importance of food fibers has led to the development of a large market for fiber-rich products, there is a trend to find new sources of dietary for foods. Fiber supplementation of foods can change their consistency, texture, and sensory of the end products, can offer new opportunities in food industry.  Conclusions. Dietary fiber can be used in various functional foods. Influence of different processing treatments (like extrusion-cooking, canning, grinding, boiling, frying) alters their properties and improves their functionality.