It is reported when posterior dislocation of the elbow with the fracture of the coronoid process is occurred, if they can 't achieve the reduction of coronoid process, the patient would have the elbow instability. That is required to open reduction of coronoid process. Limitation of the elbow motion and persistent posterior dislocation of the elbow result from failure of reduction of coronoid process in acute injury. That patients have been treated by distraction arthroplasty, total elbow replacement, arthrodesis, and coronoid process reconstruction. We experienced one case that had a excellent result from reconstruction of the coronoid process using a graft from the olecranon of same side in 28 years old man.