ObjectiveTo investigate the therapeutic effectiveness of low-power laser on myofascial pain syndrome. Methods73 self-controlled patients with myofascial pain syndrome were irradiated on myofascial trigger points with Nd:YAG laser in wavelength 830nm, power 500mW, 20 minutes per day for 5 times. At pre-and post-treatment,pain intensity and pressure pain of myofascial trigger points were checked. ResultsAfter treatment, score of pain intensity was reduced signficantly from (7.24±2.41) to (2.21±1.22) (P<0.001). The pressure pain of myofascial trigger points were improved . Conclusions Low-power laser can reduce the pain intensity and increase the pressure pain threshold of myoficial trigger points.