Abstract: ObjectiveTo probe into the effect of He-Ne laser on superoxide dismutase(SOD),malon-dialdehyde (MDA)and nitric oxide(NO)in the serum of the rats with myocar dial infarction.MethodsThe myocardial infarcted rats were ir adiated on their precordial regions by HE-Ne laser with certain intensity for different time to observe changes of serum free radical levels.ResultsCompared with the control group(44.28U/ml),the content of SODin myocar dial infarcted rats irridiated by He-Ne laser for 10 and 20 min increased significantly(48.86,50.22 U/ml,P<0.05).Compared with the control group(4.78 nmol/L),the content of serum MDA decreased significantly(3.94,3.99 nmol/L,P<0.05).By 20min irradiating,compared with the control group(286.46μmol/L),the content of NO in rats.serum increased significantly (388.86μmol/L,P<0.05).ConclusionHe-Ne laser irradiation on the precordial region has certain significance in treating coronary heart disease and myocardial ischemia.