Of 242 posterior fracture-dislocations of the hip, of which 150 had been followed for from four to twenty-seven years (over-all average, seven years and three months), 112 were treated by closed reduction; and fifty-six, by primary open reduction. Satisfactory results were obtained in 12 per cent of the hips treated by closed reduction, in 42 per cent of those treated by closed reduction followed by open reduction, and in 63 per cent of those treated by primary open reduction with removal of all loose fragments of bone and cartilage and restoration of stability by internal fixation of the fracture of the acetabular rim offers the best prognosis.