This study was performed to compare the effects of direct current with ultrasound on fracture healing. Thirty-two rats were subjected to the experiment. Each rat's right legs were used as the experimental sample, and their left legs were used as the control. Four groups were formed, each consisting of 16 ultrasound, 16 electrostimulation, 16 ultrasound control, and 16 electrostimulation control animals. Fibular osteotome was applied to the rats under anesthesia. In the electrostimulation and electrostimulation control groups, a stainless steel cathode electrode was installed in the fractured side. In the electrostimulation group, 10 mu A of direct current for 30 min, using a semi-invasive method, was given one day after fracture, for 15 days. On the control side, the aforementioned protocol was followed but sham treated. The ultrasound group was treated with 0.1 W/cm(2) ultrasound for 2 min every second day for 6 days after fracture (4 times). Rats were killed on the 7th and 14th days to investigate the macroscopic, radiologic, and histopathologic parameters of fracture healing. There was a difference (P < 0.05) between the electrostimulation and the electrostimulation control groups on the 7th day. There was a difference (P < 0.05) between the ultrasound and ultrasound control groups on the 14th day. After statistical evaluation of the experimental results, it was found that in both the ultrasound and the electrostimulation groups, the fracture healing had been accelerated more so than in the control groups. There was no observed statistical difference between ultrasound and electrostimulation effects.