In a prospective, randomised controlled trial, 68 children who had a completely displaced metaphyseal fracture of the distal radius were treated either by manipulation (MUA) and application of an above-elbow cast alone or by the additional insertion of a percutaneous Kirschner (K-) wire. Full radiological follow-up to union was obtained in 65 children and 56 returned for clinical evaluation three months after injury. Maintenance of reduction was significantly better in the K-wire group and fewer follow-up radiographs were required. There was no significant difference in the clinical outcome measured three months after injury. Seven of 33 patients in the MUA group had to undergo a second procedure because of an unacceptable position compared with none of the 35 in the K-wire group (chi-squared test, p < 0.01). One patient in the K-wire group required exploration for recovery of a migrated wire. We conclude that the use of a percutaneous K-wire to augment the reduction of the fracture in children who have a completely displaced metaphyseal fracture of the distal radius is a safe and reliable way of maintaining alignment of the fracture.