The treatment of residual hip dysplasia can be carried out using different methods which range from T.H.R. to the various kinds of osteotomy. Among these, Chiari osteotomy still holds a prominent position, although new techniques have decreased its indication. Following the results of 13 years’ experience with this procedure, the Authors confirm that Chiari osteotomy permits the reduction of the acetabular inclination and a wider articular coverage of the femoral head on all planes. Nowadays, this long experience together with an accurate knowledge of the biomechanical effects of the procedure should be able to guide the orthopaedic surgeon, with adequate accuracy, to the choice and the indications of this complex but effective procedure.