Non-invasive treatment of non-union of diaphyses by application of the shock waves known from lithotripsy has proved successful in three out of four cases. Two thousand shock waves with a single-wave energy of 18 kV were applied by the MFL 5000 and HM3 Lithotripters of the Dornier Medizintechnik Company with manual detection of the lesion. The shock waves induced a kind of callus formation in the non-union soft tissue within about 6 weeks, which was successfully maintained and transformed into bony union in all cases but one by dynamic fixation less rigid than a plaster cast. Four cases are documented and the effects of the shock waves and principles of bony union discussed.