A case of familial congenital simple short femur is described in an 8-year-old brother and an 8-month-old sister, associated with other congenital defects in the lower extremities. In the case of the sister, early intrauterine detection and follow-up were possible. This early intrauterine detection by means of ultrasound may enable us to calculate the ratio between the length of the short femur and that of the normal one and to plan for corrective surgery at a later date.