To assess the risk of injury to the posterior interosseous nerve (PIN) in transosseous locked nailing of the radius, the relationship of the PIN to the surgical zone was studied in five pairs of fresh frozen adult cadaver arms. A static locked intramedullary nail was inserted in each radius using the recommended surgical technique. A formal dissection of the radial nerve and its branches was then performed to document the relationship of the PIN to the radial head in neutral, pronation, and supination also was measured. In no specimens was the PIN injured by the screw insertion. However, in two specimens (right and left arm of the same donor) the PIN was 1 mm and 2 mm, respectively, from the screw insertion site. The average shortest distance from the PIN to the screw was 11.3 mm. As measured along the mid-shaft of the radius, the average distance from the radial head to the PIN was 36.2 mm in 90 degrees supination, 46.7 mm in neutral, and 56.9 mm in 90 degrees pronation. Transosseous static locked nailing of the radius is feasible, but the surgeon and patient must be aware of the risk of possible injury to the PIN. To minimize this risk, we suggest that the proximal locking screw should be inserted from a direct lateral entry at < 30 mm from the radial head with the forearm in neutral rotation.