Cubitus varus deformity caused usually by malunion in supracondylar fracture or epiphyseal injuries of the elbow joint, but the other causes of cubitus varus deformity have not been reported. 7 cases of cubitus varus deformity were found among the patients in Sam Yook Childrens Rehabilitation Center in Oct. 1981 all of whom used crutches in order to ambulate due to late sequele of poliomyelitis. The results were as follows. l. After long-term crutch walking, cubitus varus deformity and bowing around the proximal forearm were seen among the patients who mis-used the crutches. 2. Gross carrying angle was greater than radiographic carrying angle and it caused by hypertrophy of the extensor muscle group in forearm and bowing around the proximal forearm. 3. Etiologic factors of the cubitus varus deformity were considered to be improper measurement of the crutches, degree of paralysis of lower extremity and duration of the crutch walking, etc. 4. The mechanism of this deformity could be explained biomechanically by the abnormal axial loading onto the elbow following long-term crutch walking. 5. The correct measurement of the crutches and proper flexion of the elbow during crutch walking were stressed.