The fracture of the humerus during arm wrestling are uncommon, but may occur in the shaft or medial condyle. In the shaft of humerus, the fractures are usually spiral and between the middle and distal third, with or without neurological involvement. A case of a comminuted spiral fracture with butterfly fragment of the distal third of the humerus is reported which had occurred during arm wrestling and was treated by open reduction and internal fixation. The possible mechanism of injury and the question of treatment are discussed.