Objective:The effects of He-Ne Laser Irradiation on peripheral blood serum IgG in Mice were studied,in order to illustrate mechanism of the immune modulation effect of He-Ne laser irradiation with the concentration changes of peripheral blood serum IgG in mice. Methods:By irradiating upon the inner corners of the mice eyes with He-Ne laser at five different dosages of 7.33, 11.00, 14.67,22.00 and 36.67J/cm 2 for eight days,the concentration of peripheral blood serum IgG were monitored kinetically at the 3rd, 6th, 9th, 13th and 17th day after laser irradiation. Results:The values of peripheral blood serum IgG increased in some degree at the 3rd,6th and 9th day in the groups of 7.33,11.00, 14.67 and 22.00J/cm 2, while the values decreased significantly in the group of 36.67J/cm 2. Conclusion:He-Ne laser with the proper dosages showed the up regulation effects on the concentration of peripheral blood serum IgG in mouse;while the large dose showed the down regulation effects.