A traumatic pneumothorax (collapsed lung) can be a life-threatening injury if it is not recognized and treated immediately. An 18-year-old high school athlete wearing rib protection sustained a pneumothorax while playing varsity football. On-site evaluation raised suspicions that the injury could be more than a rib contusion. Further examination by the team physician suggested a possible rib fracture and pneumothorax. The athlete was transported by ambulance to the hospital for x-rays and confirmation of the physician's diagnosis. The athlete was hospitalized for 2 weeks and upon release was allowed to return to school with restricted activity. This article alerts the athletic trainer to an infrequent but serious injury and discusses the signs, symptoms, and basic care instructions for a suspected pneumothorax.