It may be difficult to distinguish industrial accidents from suicide attempts or even assaults or homicide. Nail guns are relatively new industrial tools that can produce severe or fatal injuries. The configuration of the nail on patients' radiographs after such injuries can be helpful in determining the cause of injury. Steel nails that are bent are due to a ricochet and thus indicate accidental injury. Straight-nail injuries to the co-workers of nail-gun users are most likely due to over-penetration of the substance being nailed or accidental mid-air firing; however, intentional injury cannot be ruled out. Extremity injuries caused by straight steel nails in nail gun users are the result of carelessness or poor technique, but suicide should be considered when straight nails cause wounds to the chest, head, or abdomen.