The ultrasonic stimulation of bone growth was investigated in an experimental work in which a set of 45 rabbits were studied according to the following procedure: a) bilateral osteotomy of fibula (23 animals) and bilateral drilled holes on the cortex of femur (22 animals); b) exposure of ultrasound for 15 min per day. c) Radiological and histological evaluations of the progress of the callus; d) photography and measurements of the area of the callus; e) graphical comparisons using the results between controls and stimulated limbs. Pulsed ultrasound, in the form of short bursts, was used at low intensities (below cavitation threshold) so that the temperature variation, at the osteotomy site, was of the order of 0.01 degrees C (constant) a fact that reinforces the assumption that the stimulation mechanism due to the appearance of electric potentials is of non-thermal origin such as that caused by piezoelectricity.