Congenital coxa vara with severe angulation is a difficult lesion to treat and of uncertain outcome. Many valgus osteotomies have resulted in failure because of inadequate correction or recurrence of deformity. The 27 cases described confirm this view. Out of 18 cases whose results are known, only four were good, compared with six fair and eight bad results. The causes of these failures arise from technical difficulties in the operative procedures, their inadequacy, significant muscle tension and malformation of the growth plates. An effective and lasting valgus is only possible if the internal fixation is well applied in the femoral neck, with a pin inserted into its axis. A moderate shortening avoids excessive tension in the region of the joint.