The Cornelia de Lange syndrome is characterized by severe growth and mental retardation; typical facies; low-pitched, weak, growling cry, and various bone abnormalities, as was first described by Cornelia de Lange in 1933. On the other hand, Legg-Perthes disease is the condition, in which avascular necrosis of the femoral head develops, as was first described by Legg, Calve and Perthes in 1910. Review of the worlds literature disclosed only one case of Legg-Perthes disease associated with Cornelia de Lange syndrome. We experienced a case of Legg-Perthes disease associated with Cornelia de Lange syndrome in a 8 years old boy, which was treated surgically for Legg-Perthes disease. A brief review of literature was made.