Little is known about the relative injury risk of obese adolescent football players. Two high school varsity teams were followed prospectively for injuries after measurement of height, weight, and triceps and subscapular skinfolds during the preseason. Certified athletic trainers who were present at all practices recorded all injuries that required a player to miss at least one practice or game. In all, 98 players were enrolled in the study. Twenty-eight injuries were documented in 24 different players. There were 27 (28%) players with the sum of skinfolds ⩾ 95th percentile for age; eight of them had nine injuries. The overall prevalence of injuries per player per season was 0.28 for players ⩽ 95th percentile and 0.33 for players above this percentile (not significant). High body mass (body weight >90 kg) was associated with a 2.5 times higher relative risk of injury. While this study did not find evidence for an overall higher injury rate in overly fat high school football players, an alarmingly high incidence of obesity was found in this athletic population.