Limb lengthening operations were first used at the beginning of this century, they were, however, performed more frequently only in the fifties. The various, continuously elongating devices have made possible a substantially greater lengthening than earlier. Wide-range investigations were begun with the various distraction devices and the results were examined in regard to the site of lengthening, the injury of the periosteal and endosteal vascular supply during the operation and the extent and rate of the lengthening. Detailed results of 224 lengthening operations performed in 191 patients are presented in Tables 1 to 8. Attention is called to the fact that the operation should be performed strictly individually, and the patients should be well prepared to the operation and followed carefully. The number of complications increases in direct ratio with the measure of lengthening, the end result is, however, influenced only by a minor part of the complications.