The protective effect of trimetazidine against myocarditis induced by coxsackie virus B3 (CVB3) in mice was investigated.Myocarditis in Balb/c mice was induced by CVB3.Then the mice were randomized to blank group, myocarditis control group and trimetazidine (low, medium, and high concentrations) treatment groups for 7 days.Serum levels of IFN-γ, TNF-α, IE-10, and IE-12 were determined on mice, meanwhile the virus liter of the myocardium, pathol. change, MDA concentration, SOD, and CAT activities were detected.As compared with myocarditis control group, in groups treated with trimetazidine, serum levels of IFN-γ, IE-10, and IE-12 were increased significantly, but the change in serum TNF-α level was not significant, and the virus titer of myocardium was decreased, and pathol. lesions of myocardium were ameliorated, and the MDA concentration was decreased, but SOD and CAT activities were up-regulated (P < 0.05).In summary trimetazidine had protective effect on CVB3-induced myocarditis in mice by down-regulating the virus titer of myocardium and attenuating the degree of myocardial pathol. injury.