Fractures of the shaft of the humerus due to muscle violence esp. from throwing hand grenades are uncommon. Even so there are reports from many authors documenting such fractures from throwing a javerin, baseball, hand grenade and arm wrestling. Fractures of this type are usually spiral in nature; located between the middle and distal third of the humerus. We have treated four such cases during activities in which hand grenades were thrown. These fractures were sustained by military recruits in the Department of Orthopaedic Surgery, Capital Armed Forces General Hospital from Jan. 1980 Dec. 1980.