Generally, buckwheat has been regarded as a crop of secondary importance in many countries. In vitro functionalities of buckwheats as a food were evaluated in this study. Five of buckwheat cultivars were extracted with methanol, and the extractant were dried and lyophilized, separately. Or water soluble buckwheat components were digested with the commercial enzymes and the obtained protein hydrolysate was again fractionated by acid precipitation. The antioxidant capacity of the methanol extracts determined using Fe2+-ascorbic acid system was dependent ont the cultivars: The extract of Suwon 4 showed 3.3 times stronger activity than ascorbic acid in terms of IC50. Also, the extracts of buckwheats inhibited efficiently the activities of $alpha$-amylase and lens aldose reductase. Buckwheat soluble protein or rutin suppressed the in vitro activities of angiotensin-converting enzyme, and the inhibitory degree depended largely on the cultivars. Buckwheat proteins exerted higher hydrophobicity being related to the sterol binding capacity than casein. The results suggested that buckwheat seeds may be desirable and functional food resources in human living in current society.