Congenital fibrous bands may be found at the gluteus maximus, the gluteus medius,thequadriceqs,the triceps and the deltoideus muscles. Congenital fibrous bands of both gluteus maximus muscles are rare and cause extension contracture of the hip joints. We experienced a case of congenital fibrous bands of both gluteus maximus muscles associated with severe limited flexion of both hips. Almost full flexion of both hips was obtained by excision of the congenital fibrous bands.