Introduction Diaphyseal forearm fractures are common in children and adolescents. Intramedullary fixation with flexible nails has a high success rate. Complications related to the insertion of the radial nail include injury to the superficial branch of the radial nerve and rupture of the extensor pollicis longus (EPL) tendon. Materials and Methods We report a series of nine patients who sustained an EPL injury related to the insertion of an elastic intramedullary nail into the radius. Results All nine patients underwent operative management, consisting of either EPL release, EPL direct repair, or tendon transfer (using extensor indicis proprius). In all cases, the nail entry site was directly related to the location of EPL. In many of the cases the EPL dysfunction occurred early on but it's recognition was often delayed. Conclusion Based on our findings, we recommend the use of a radial entry point. For surgeons who prefer the dorsal entry point, we recommend that they use an incision which allows visualisation of the extensor tendons and that any post-operative EPL dysfunction is addressed promptly.