The hypothesis that a causal relationship exists between unequal leg length and disorders in the back or lower extremities has been hard to prove. However, at the present time there is scientific documentation of an association between a difference in length of more than 1 cm and low back pain. Thus, in children with one leg one centimetre or more longer than the other, and in adults with symptoms, the discrepancy should be adjusted, especially if a lumbar scoliosis in the standing position has been documented radiographically. A difference in length of less than 2 cm should be treated by raising the shoe. An established or estimated difference of more than this is usually corrected by surgery, either by epiphysiodesis or by shortening or lengthening osteotomy. In adults with a moderate difference in leg length, a raised shoe test is recommended in order to evaluate the effect of a correction in practice before osteotomy is performed.