The results of prospective treatment of 31 patients with subtrochanteric fractures using the Derby intramedullary nail are presented. The nail design, plus cerclage wires in unstable cases, allows axial compression of the fracture, to give rigid fixation and load-sharing between bone and nail. Twenty-seven patients were followed up for an average of 21.7 months. There were no mechanical failures of the nails, and all 27 fractures united, two in minimal varus. Relatively early mobilization of the patients with isolated fractures occurred.