Objective:To investigate the protective effect of coenzyme Q10 emulsion on myocardial injury in mice induced by adriamycin and its mechanism. Methods:Coenzyme Q10 capsules and emulsion were administered intragastrically and intravenously to the mice for 5 days,respectively. In the 3rd day adriamycin was given intraperitoneally to establish myocardial injury mice model. After 72h,the level of SOD,CK,MDA and LDH in myocardial cells were tested,as well as the ECG. The level of p53 protein in myocardial cells was assayed by immunohistochemical method cells. Results:Coenzyme Q10 emulsion improved the level of SOD,CK,MDA and LDH in mice myocardial cells,but with no dose-dependency. Also the incidence of arrhythmia was depressed by coenzyme Q10 emulsion. Conclusion:Coenzyme Q10 emulsion has a protective effect on myocardial injury induced by adriamycin,and its mechanism may be related to the antagonism action.