Chitosan Oligosaccharide is a non-toxic functional amino sugar of low molecular weight. It is a mixture of oligomers of D-glucosamine. The degree of polymerization of the oligomer is about 20.3. Its molecular weight is average 3,000-5000. Chitosan oligosaccharide, which is a low-molecular chitosan, is obtained by transformating chitosan under the action of enzymes. Oligosaccharide application prevents accumulation of fat cells in internal organs, in particular, in kidneys after alcohol intake. Oligosaccharides significantly prevent negative impact of the alcohol on the liver. Oligosaccharide plays a remarkable role in the liver function control preventing growth of alcoholic hepatosis.