We describe a Japanese brother and sister with Martsolf syndrome. They had short stature, severe mental retardation, cataract, hypogonadism, craniofacial dysmorphism, and bone and joint symptoms including scoliosis, lax finger joints, and talipes valgus. Previously undescribed findings included proximal femoral epiphyseal dysplasia reminiscent of Legg-Calve-Perthes disease in both patients, and Klippel-Feil malformation and osteopathia striata in one patient. Brain MRI showed mild frontal and temporal lobe atrophy, and mild ventricular enlargement. Severe GH deficiency was demonstrated after insulin tolerance and glucagon/propranolol tolerance tests. No responses to serum LH and FSH after a gonadotropin-releasing hormone (GnRH) test suggested secondary hypogonadism, that is, hypogonadotropic hypogonadism, due to hypothalamus-pituitary axis insufficiency in both patients.