Spontaneous correction of deformity is produced by bone remodelling during the period of growth. The purpose of this experimental study was to find out in which phase and to what extent asymmetrical epiphysial growth participated in the correction of an experimentally produced deformity. Transverse wedge osteotomy was performed in the legs of twenty growing mongrel dogs, the fragments being fixed with bent AO-plates. From radiographs taken at intervals of two weeks the epiphysial and axial angles were measured. Nine dogs were given tetracycline ten to twenty days before death and the cut surfaces were photographed in reflected ultra-violet light. It was found that epiphysial growth played an important role in the remodelling process. This factor accounted for roughly half of the total correction and averaged 12-5 degrees during the observation time of 160 days. The greatest correction occurred during the first weeks. Correction of the epiphysial angle took place with acceleration of growth.