Osteogenesis imperfecta is rare disease in Korea. The patient is 18 year old Korean male with complaint offrequent fracture of extremities and bowing deformity of lower extremity. Skull X-ray shows mosaic pattern ofmultiple wormian bones on occipital bone. Chest PA shows no significant abnormality but slender ribs. Spinereveals diffuse osteoporosis and fish vertebra deformity. Extremities are hypoplastic and osteoporotic withfracture lines, fresh or healed. Bowing deformity is typical in lower extremity.