In briefA 17-year-old male high school football player sustained two mild concussions in 7 days. Five weeks later, he ran 50 yd in a game and fell to his knees complaining of severe headache, nausea, facial pain, and difficulty breathing. An immediate on-field physical examination was normal, but the boy progressively became lethargic, stuporous, then comatose. CT scan revealed a right subdural hematoma, perhaps a long-term complication of the two mild concussions. Rules requiring neurocognitive testing after head injury and a physician's written clearance to return to play may be needed to prevent life-threatening injury or permanent neuropsychological sequelae in head-injured athletes.