The clinical features and results of treatment were reviewed in 17 traumatic palsies of the posterior interosseous nerve. Variations in clinical features depended on whether the recurrent branch or descending branch of the posterior interosseous nerve was injured. Seven patients had nerve repair, and two were treated by tendon transfers. Eight patients were treated conservatively. Sixteen of 17 patients recovered to more than M4 motor power at final follow-up. Associated muscle damage worsened the functional result.