The complete fracture-separation of proximal radial epiphysis is a comparatively rare injury In the original discription about this injury by Jeffery, the complete displacement of fracture was produced by a result of spontaneous reduction of dislocated elbow after initial nondisplaced fracture of radial neck with dislocation of elbow, We have experienced of development of complete posterior displaced radial neck fracture after reduction of the posterior elbow dislocation.