Structuring and phenotyping genetic diversity is an important aspect of the work with breeding sources and materials. In the Introduction, the authors pointed out the role of N.I. Vavilov's scientific foresight in defining the topical trend in researching the genetic diversity of a crop, particularly the analysis of its biochemical composition. As the target of their research, the authors chose biochemical characters identifiable in the process of metabolomic analysis conducted by means of gas chromatography with mass spectrometry. Materials and methods. The object was the grain of naked and covered forms of common oat (Avena sativa L.) from the collection held by the Oat, Rye and Barley Genetic Resources Department of VIR. The analysis of oil fatty acid content and metabolomic research were performed using the method of gas chromatography with mass spectrometry on the chromatograph Agilent 6850 (USA). Results. The obtained metabolomic spectra which reflected the metabolomic status of genotypes of various ecogeographic origin were compared among themselves using statistical (principal component) analysis methods. The results of the comparison are discussed by referring to the most important groups of metabolites significant for forming the traits of resistance to stressors as well as the characters related to food qualities of grain products. Special attention has been paid to biologically active compounds determining the functional value of the products for human nutrition: the sum of phenolics in covered forms is five times higher than that in naked ones and the content of glycine in covered forms is five times higher than in naked grain, with a similar proportion in the content of organic acids, sugars, etc. Conclusion. Differences between metabolomic profiles of naked and covered forms have been detected and statistically verified. Accessions with the most optimal nutritional composition have been identified for food purposes and for the development of resistance to biotic and abiotic environmental stresses.