Polyphenols distributed widely in vegetables, fruits and teas are likely to have beneficial effects on human health, because of their antioxidative, antimutagenic, and antitumor activities. The total polyphenol content in 24 species of wild grass was measured and compared with that in 16 vegetables by the Folin-Denis assay, using caffeic acid as a standard. The polyphenol content per 100 g of fresh plant was more than 0.1 g in all of the wild grass species, but in only 7 types of vegetable. Furthermore, values over 1 g were found in 6 of the wild grass species, but in none of the vegetables. These results indicate that wild grass may be a good source for physiologically active polyphenols.