The purposes of this study is to discuss and analyze the effect on the recovery from cut in sciatic nerve. This study used 9 weeks male rats of Sprague-Dawley family. Rat in groups 4 were treated with pulsed therapeutic ultrasound for 3 minutes. 3 times weekly at 3MHz respectively (intensity; $0.2W/cm^2,;0.5W/Cm^2,;10W/cm^2$); rat in group 1 received placebo ultrasound. In addition, changes of serum aspartate amino-transferase(AST) and creatine phosphokinase(CPK) levels were also demonstrated with diameter of individual muscle fasciculate and number of muscle fiber in each of three types of muscles located in gastrocnemius, soles. The results of comparing the changes in groups are as follows; 1. We found out that hypertrophic epineurium was present in sciatic nerve injured ultrasound treatment of groups. 2. In the gastrocnemius morphological investigation of the group I (control group), severe muscle atrophy were observed at the 7th days of the sciatic nerve injury. however, muscle atrophy of the group IV ($1.0W/cm^2$) were slightly recovered at the 14th days after treatment ultrasound. At the 28th days, muscular fibers were formed in polygon and were significantly recovered. 3. C-fos immunoreactive of the group II ($0.2W/cm^2$), III ($0.5W/cm^2$) were remarkably increased at the 1th day after treatment of ultrasound. Group IV were markedly deceased. 4. Brain-Derived Neurotrophic Factor(BDNF) immunoreactive of the group II, III were increased after 7 days of the sciatic nerve injury. Group IV were markedly increased from 14th days to 28th days after treatment of ultrasound. 5. A significant increase of serum AST levels were demonstrated in control group. However, serum AST levels of massage groups were significantly decreased compared to that of control group in followed order ; ($0.2W/cm^2<0.5W/cm^2<1.0W/cm^2$). 6. A significant increase of serum CK levels were demonstrated in control of group. However, serum CK levels of massage groups were significantly decreased compared to that of control group in followed order ; ($0.2W/cm^2<0.5W/cm^2<1.0W/cm^2$). The above results suggest that ultrasound treatment after peripheral nerve injury might reduce noxious stimuli, facilitate nerve recovery and effective in the functional improvement delaying muscle atrophy or degeneration.