Traumatic dislocation of the hip presents serious problems that may lead to avascular necrosis, nerve palsy, post-traumatic arthritis even when reduction is promptly and adequately carried out. Among them avascular necrosis is the most important prognostic factor, so the early detection of this complication has critical significance for final result. Bone scan has been considered one of early diagnostic test, but recently MRI replaced its role for imaging in the detection of early AVN, treatment monitoring and prediction of prognosis. Authors prospectively studied the early finding of MRI to detect avascular necrosis of the femoral head and to predict prognosis in traumatic hip dislocation and fracture-dislocation. From December 1990 to November 1994, 12 case of dislocation and fracture-dislocation of the hip were studied . In follow up period ranging from 19 months to 65 months, 10 case had excellent or good result. All cases had abnormal MRI finding such as paraarticular edema, capsular bulging, joint effusion, femoral head fracture, but findings such as femoral head signal changes were dectected in only 3 cases. Among the 3 cases, 1 case had developed AVN and 2 cases were uneventful. Other complications were 3 cases of posttraumatic arthritis, 2 cases of incomplete sciatic nerve palsy, and 1 case of heterotrophic ossification. Although early MRI finding at posttrauma 2weeks gave less specific information, it could give good information for risk group and follow up control with more cases. Although it is expensive, MRI can be one of the most reliable reference in early diagnosis of AVN and prediction of prognosis in traumatic dislocation and fracture-dislocation of the hip with non-invasive method.