In the paper ADL (activity of daily living) was cxamined carefully on those disabled persons registered in Okayama Prefecture, who had discrepancies in length of the lower extremities due to such causes as anterior poliomeylitis, congenital dislocation of the hip joint, fracture and osteomyelitis. In addition, the follow-up studies were conducted on those patients who underwent the operation for the correction of unequal leg length by epiphyseal stapling or lengthening of the lower leg in the Department of Orthopedic Surgery of Okayama University and Kochi and Kagawa. Prefectural Rehabilitation Center for Crippled Children (Kojikaen and Hikarigakuen). From the results of these studies the following conclusions were drawn. 1. In studying the relationship between the unequal leg length and the ADL, not only the length of leg itself causes inconveniences but also original disease or lesion has a great bearing on ADL. Viewing only from the length of leg, it seems that the difference of 2.5-3cm in the leg length is the boundary in adults. 2. On the basis of expected average correction, the equalizing leg length by epiphyseal stapling is an effective and safe method. 3. The lengthening of the lower leg is a reliable method for a wide range of skeletal age provided that the care is taken to prevent complications.