Dietary fibre is a group of food components which is resistant to digestive enzymes and found mainly in cereals, fruits and vegetables. Dietary fi ber and whole grains contain a unique blend of bioactive components including resistant starches, vitamins, minerals, phytochemicals and antioxidants. Dietary fi ber which indigestible in human small intestinal, on the other hand digested completely or partially fermented in the large intestine, is examined in two groups: water-soluble and water insoluble organic compounds. Dietary fi ber can be separated into many different fractions. These fractions include arabinoxylan, inulin, pectin, bran, cellulose, β-glucan and resistant starch. Dietary fibres compose the major component of products with low energy value that have had an increasing importance in recent years. Dietary fibres also have technological and functional properties that can be used in the formulation of foods, as well as numerous beneficial effects on human health. Dietary fibre components organise functions of large intestine and have important physiological effects on glucose, lipid metabolism and mineral bioavailability. Today, dietary fibers are known to be protective effect against certain gastrointestinal diseases, constipation, hemorrhoids, colon cancer, gastroesophageal reflux disease, duodenal ulcer, diverticulitis, obesity, diabetes, stroke, hypertension and cardiovascular diseases. In this review the physicochemical and biological properties of dietary fibers and their important implications on human health will be investigated.