Under this study, a yield analysis of covered grain and naked grain oat strains was carried out. The data originated from the preliminary trial experiments accomplished in 2008. There were examined: 27 covered grain oat genotypes and 2 standards in 6 environments, and 12 naked grain oat genotypes and 2 standards in 5 environments. A graphical bi-plot method of GGE type was applied to the yield analysis (the GGE effects comprise a sum of main effects of G genotypes and the effects of GEI genotypic environmental interaction). Based on the GGE bi-plots, the genotypes were characterized and those showing the highest GGE effect in each environment were pointed out. From among the naked grain oat strains in all the environments studied, STH6264 and CHD1368 had the highest yield and were well adaptable, and as for the covered grain oat strains: CHD1534, STH149, STH6038, STH12, KREZUS, POB3107. A dynamic concept of stability was studied, i.e. those oat genotypes were identified, which did not show any genotypic environment interaction. The most stable naked grain oat strains were: STH6294, CHD1408, CHD1438, CHD2567, CHD1368 and the most unstable: STH108 and STH6315. The most stable covered grain oat strains were: CHD1156, CHD3833, STH12, CHD1193 and the most unstable STH132 and POB3672. An ideal genotype was determined. Among the naked grain oat strains, STH6264 was the most ideal genotype, whereas among the covered grain genotypes: STH12.