In the introduction the authors give account on the quickly changing of several groups of feed additives. After reviewing the general reasons of using different enzymes as feed additives some general physiological observations are summarized in connection with the feeding of nonstarch polysaccharides of grain seeds. General properties of outlined enzymes were described, and the detailed review of those eight enzymes (beta-glucanase, xylanase, pectinase, cellulase, protease, phytase, amylase, lipase) which are used as feed additives is given. Finally the authors give detailed account of the favourable physiological observations, collected in connection with enzymes, used as additives in feeding of poultry and pig.