Leg lengthening has been a procedure of last resort due to its high complication rate & significant morbidity with a relatively long period of disability during the process even when no complications occur. The new techniques of lengthening hold promise that orthopedists will be able to achieve more length with fewer complications. It is interesting to note, however, that, while it is the technology of these techniques that has stimulated the greatest enthusiasm, it is the biologic principles that are likely to offer the greatest ultimate benefit. The modern era of leg lengthening has therefore brought two things: new technical versatility to correct complex & coexisting deformities & new concepts of the biology of lengthening that are not device specific & can be applied with most lengthening devices.