To clarify that the mixed nerve silent period (SP) and H reflex from soleus muscle may become an index expressed neuro-muscular function after reconstruction of anterior cruciate ligament (ACL), we studied the alteration of SP and H reflex from the soleus muscle in the patient with ACL reconstruction. Subjects were three patients with after ACL reconstruction, who were two male athletes (case A and B) and a female aerobics instructor (case C). Recording of SP and H reflex was performed longitudinally from one month post operation to six months post operation. As a result of this study, in case A, following findings were appeared; shortening of duration of SEP increasing the coefficient of variation of SP and increasing the amplitude ratio of H/M in non-operative side at the same time when his overusing activity of non-operative side. With case B, an appearance of long latency reflex (LLR) and an increase of coefficient of variation of SP in the operative side were verified in the period when many assists were required in order to correct motion image in rehabilitation. Concretely, from after the reconstruction over 5 months, LLR was appeared in SP of operative side, and increases of coefficient of variation was most remarkably in 4 months after the reconstruction, amplitude H/M ratio of operative side showed high value in 4 months after the reconstruction. With case C, remarkable problematical point was not found at the time of activity of daily life (ADL) acquisition and occupation return. So, with case C, feature findings of both SP and H reflex were not appeared. The results suggested that SP and H reflex from soleus muscle have become an index expressed neuro-muscular function of lower extremity and supra-spinal function in the patient after reconstruction of ACL.