Twenty-six high school football teams playing 228 games in the Seattle metropolitan area were prospectively studied during the fall of 1970. Eighty games were played on a synthetic field and the remainder were played on grass fields. Injury rates for games played on the synthetic surface were significantly higher than those played on grass. The incidence of serious injuries was also higher on synthetic surfaces. The higher injury rates for games played on synthetic surfaces was almost wholly a function of die even higher injury rate on the artificial surface in the dry condition. The role played by field surface in die production of football injuries merits further investigation. These investigations should include die other types and models of synthetic turf currently available.