Army cadets who had sports injuries to their quadriceps femoris during one academic year were grouped according to the severity of the contusion-mild, moderate, or severe. The extent to which knee flexion was limited (< 90, 90 to 120, and > 120 degrees) corresponded to the severity of injury as did time lost from duty. Sixty-five injuries were found—forty-seven mild, seven moderate, and eleven severe. The patients with moderately severe injuries had thirty-three to ninety-five days of disability and those with severe injury twenty-eight to 180 days. Myositis ossificans was more common in patients with severe injuries and those with moderate injuries (thirteen of the eighteen patients), but it did not correlate with the duration of disability and none of the patients had permanent disability.