Study of 21 cases of femoral valgisation osteotomy, with a minimum follow-up of 5 years, confirms the value of this operation in the treatment of certain types of osteoarthrosis of the hip, and above all those types in which there is an inferior capital osteophyte. The indications depend upon: --clinical features: as in the case of all osteotomies, mobility must be at least equal to 70 degrees flexion. --radiological findings: reposition films in adduction should show widening of the joint space and above all improved congruence. The presence of geodes and lack of cover of the femoral head are not, in themselves, contraindications. The operation involves, in addition to valgisation inter-trochanteric osteotomy, relaxation of the peri-articular muscles (psoas, adductors, gluteus medius) in order that the relative lengthening of the upper end of the femur related to ventricalisation of the neck should not be in contradiction with the usual principles of surgery for osteoarthrosis. Valgisation osteotomy results in an increase in weight-bearing surfaces and thus a decrease in unit pressure. Indicated and performed in this way, this operation gives highly satisfactory and durable results, as shown by the follow-up period of our own cases.