Cereal grains and wholegrain cereal products (rich in fibrous polymers) are the excellent sources of numerous unique substances rating among biologically active compounds such as dietary fiber (arabinoxylans, beta-glucans, cellulose, lignin and lignans), sterols, tocopherols, tocotrienols, alkylresorcinols, phenolic acids, vitamins and microelements. Cereals have been staple foods both directly for human consumption and ready available to the human diet. The major cereals consumed worldwide are wheat, rice, maize, barley, oats, rye, millet, sorghum. Bioactive compounds of whole-grains are present in the bran/germ fraction of cereal-grains and least in endosperm. The bioactive components in cereals help in reducing the risk of chronic diseases act as a functional ingredient. Bioactive compounds in whole-grain cereals have not received as much attention as in fruits and vegetables due to difficult in extractions and some have antinutritional role. These health benefits are achieved through multifactorial physiological mechanisms including antioxidant activity, mediation of hormones, enhancement of immune system and facilitation of substance transit through the digestive tract, butyric acid production in the colon, and absorption.