PURPOSE: To evaluate the cause and surgical outcome of extensor pollicis longus rupture after distal radius fractures. MATERIALS AND METHODS: Nineteen cases in which the patients underwent surgical treatment for rupture of the extensor pollicis longus after distal radius fractures were followed for more than one year. Among the nineteen cases, fourteen extensor pollicis longus ruptures occurred after conservative treatment, four occurred after closed reduction with K-wire fixation, and one occurred after open reduction and internal fixation with a plate. All cases were treated by extensor indicis proprius transfer. RESULTS: Extensor pollicis longus ruptures were caused by K-wire irritation in two, by a protruding screw tip in one, and by a callus in one. In the conservative treatment group, tendon ruptures were diagnosed at an average of 3.1 months (0.7~17). Tendon ruptures were detected in the surgical treatment group at an average of 12.8 months (1~48). All the patients showed favorable recovery of the extension capability of the thumb at the final follow-up. CONCLUSION: The main cause of extensor pollicis longus rupture after distal radius fracture was ischemic damage. Therefore, during the surgery, the length and direction of screws and K-wires should be fixed carefully to avoid such damage. Distal radius fracture also requires careful observation of the extensor pollicis longus during follow-up. Furthermore, extensor indicis proprius transfer is considered to be an effective method for extensor pollicis longus rupture.