In recent years, some researchers reported that myofascia was innervated by the autonomic nervous system. However, there is no neurophysiological explanation and evidence for the effects of myofascial release(MFR). Thus, the aim of this study was to determine whether the excitability of the autonomic nervous system is modulated by MFR. In this study, thirty healthy subjects in their 20s were randomly assigned to a myofascial release group(MG) and a placebo control group(PCG); each group had 15 subjects. The MG conducted 5 minutes of cranial base release in supine position, and the PCG performed sham cranial base release. Muscle flexibility was measured with the neck range of motion and the changes of the autonomic nervous system excitability was measured by heart rate, blood pressure, and concentration of plasma epinephrine and norepinephrine. The results were as follows: 1. The percentage changes in the cervical range of motion for extension and side flexion were significantly increased in the MG, signifying that more muscle relaxation. 2. There was no significant percentage changes in heart rate, blood pressure, and concentration plasma epinephrine between MG and PCG. 3. The percentage change in concentration plasma norepinephrine was significantly different between MG and PCG. The result of this study suggests that there is no evidence that MFR can modulate the autonomic nervous system excitability.