Posttraumatic osteonecrosis of the femoral head (ONFH) is the most serious complication after fracture dislocation of the femoral head. The rate of this complication was reported to range from 1.7% to 40%. Although the development of posttraumatic osteonecrosis normally occurs within 2 years of injury, there are some reports of the late development ONFH. The authors encountered a case of posttraumatic ONFH that developed after 9 years of a Pipkin type I fracture dislocation. The patient was treated by modified transtrochanteric rotational osteotomy. We report this rare case with a review of the relevant literatures.