Most fractures of the clavicle occur as isolated injuries and resolve without complications. A rare case of pneumothorax that complicated a clavicle fracture is reported in a 19-year-old man. The pneumothorax necessitated closed-tube thoracostomy. Six weeks of splint immobilization resulted in satisfactory union of the clavicle fracture. Complete chest and neurocirculatory examinations and careful review of pertinent radiographs enabled an early diagnosis of this rare complication of a fracture of the clavicle.