Abstract: A jig for resurfacing the head of a femur comprises a centering guide defining a centering axis. It further comprises: a support suitable for fitting on a head of the femur and defining an envelope surface forming a portion of a sphere, the centering guide being fastened to the support with the centering axis aligned on a diameter of the sphere; and at least one abutment arm for coming into abutment against a predefined portion of a neck of the femur, the abutment arm being connected to the support and having a distal end that bears against the corresponding predefined portion when the support is fitted on the head of the femur with the centering axis aligned on the central axis of the neck of the femur or with a small amount of valgus.