Rheum undulatum and Rheum palmatum have been widely used as food material as well as medicinal ingredients for their therapeutic effects in oriental countries. Many kinds of herbs are being used in the manufacture of functional foods. The objective of this study was to determine polyphenol content, superoxide dismutase (SOD)-like activity, tyrosinase activity, and electron donating ability of R. undulatum and R. palmatum. Total polyphenol content were most effective in 50 and 100% ethanol extracts from R. undulatum and R. palmatum. SOD-like activities of R. undulatum extracts were higher than those of R. palmatum extracts, and water extracts of samples were highest. EDAs of R. undulatum extracts were higher (26.76-44.46%) than those of R. palmatum extracts, while those of both extracts were lower than 1.0 and 0.1% L-ascorbate. And these suggest that the extracts of R. undulatum and R. palmatum can be used as a material in functional food.