The chemical analysis of market-available white oat cultivars allows for their optimized use for processing, consumption, and in blocks of crosses. The purpose of this study was to evaluate the performance of white oat cultivars with regard to grain chemical content, to estimate the correlation between these traits, and to select potential REMAP markers for marker-assisted selection. Fifteen cultivars, grown in three environments, were evaluated for the contents of proteins; lipids; total, insoluble, and soluble dietary fiber; ß-glucan; and carbohydrates. Eight cultivars were analysed with REMAP markers. The cultivars Brisasul and UPFA Gaudéria presented higher contents of ß-glucan, while cultivars URS 21 and URS 22 had higher protein contents. For animal feed, the cultivars Barbarasul and FAPA Louise stood out with high lipid contents. Positive correlations between the contents of lipid and total dietary fiber, protein and insoluble dietary fiber, and total dietary fiber and insoluble dietary fiber were constant in different environments. Also, carbohydrate content was negatively correlated with protein, total dietary fiber, insoluble dietary fiber, and lipid content. A total of thirteen REMAP combinations were selected for variability studies regarding lipid and ß-glucan contents.