Buckwheat is a pseudocereal with important nutritional qualities and great potential for broad consumption. The study aimed to determine the biochemical composition, antioxidant properties and multi-mineral composition of the whole grains, hulls, bran, and the light flour of common (Fagopyrum esculentum Moench) and Tartary (Fagopyrum tataricum (L.) Gaertn.) buckwheat harvested in two consecutive years. Significant differences between fractions of both species were observed. On the other hand, the differences between the production years were not so significant. Biochemical and multi-mineral compositions of common and Tartary buckwheat were comparable, while significant differences between species were observed in antioxidant properties. The antioxidant potential (AOP), total phenolic content (TPC), and total flavonoid content (TFC) were higher in all fractions of Tartary buckwheat compared to individual fractions of common buckwheat. Fourteen minerals were quantified in fractions. Contents of all major minerals and most of the trace minerals were the highest in bran fraction.