In the paper, there were presented biological properties of peptides obtained from storage proteins of cereal grains. Aminoacids sequences were pointed out in the peptides released from the proteins contained in, among other things, cereals showing biological activity. It was also shown what role those peptides played in allergic reactions causing such diseases as coeliac disease or asthma. There were characterized those functions of the peptide epitops isolated from cereals proteins that were responsible for allergenic reactions. The functions of transglutaminase were discussed with regard to their role in the conversion of proteins in the lamina propria of colon. Potential applications of some enzymes (transglutaminase, proline, and peptidase) and microorganisms (sourdough lactic acid bacteria) were suggested with regard to the possibility of reducing the allergenity of plant-originating peptides. Several biotechnological methods of reducing the allergenity of cereals proteins were described.