A case of Smith's fracture of the radius with associated disruption of the distal radio-ulnar joint and fracture of the ulna is reported. Additionally, the extensor pollicis longus was dislocated palmarward between the shaft of the radius and ulna. Reduction was impossible until the muscle displacement was discovered and corrected. This soft-tissue complication should be looked for and the function of the extensor pollicis longus checked in any severely displaced Smith's fracture in which the distal radio-ulnar joint is disrupted. If open reduction becomes necessary, an approach that-exposes the fracture from the dorsum should be used.