Objective To evaluate protective effects of recombinant human thioredoxin(TRX) in myocardial injury of mice with viral myocarditis. Methods We established viral myocarditis models by intraperitoneal injection with 0.1 ml 100TCID50 Coxsackie virus 3m(CVB3m), along with tail vein injection of recombinant human TRX (2 mg/kg) for protection. The control group was given equivalent volume of normal saline. The mice were killed 7 days following the injections. Serum lactate dehydrogenase (LDH) activity was determined and myocardial injury was examined with light microscopy. Results The somm LDH activity in Coxsackie virns-infected mice [(3130.50±390.57)U/L] was higher than that of animals in the control group[ (1617.86±155.42)U/L] and that of TRX protection group[ (1959.43±540.75)U/L], the difference being statistically significant (P<0.05); there was no significant difference between TRX protection group and the control group(P 0.05). Light microscopy showed that five of the eight Coxsackie rims-infected mice had myocardial lesions, including focal myocardial necrosis and inflammatory infiltration. There was no myocardial injury in the TRX protection group. Conclusions Recombinant human TRX can lessen myocardial injuries induced by infection with CVB3m, and so can protect myocardium.