Both tibiae were osteotomised and medullary nailing in 40 rabbits. In each case the right fracture was treated with ultrasound of 0.1 W/cm2 for 2 minutes every second day altogether 4 times. The left extremity was used as control. The estimation of the mineralization took place semiquantitatively after weekly radiologic checks, this one of the callus maturation histologically in the decalcified bone. By ultrasound treatment an enlarged callus formation and an accelerated callus maturation was shown in contrast to the untreated extremity. An accelerated three-phasic fracture healing was provable by ultrasound influence. The advantage of the mineralization amounted to 2 weeks in the 4th postoperative week. The ultrasound influence of the fracture healing shows, therefore, as remedy of choice in comparison with other stimulation methods.