Abstract： Objective To evaluate the values of N-terminal pro-B-type natriuretic peptide (NT-proBNP),cardiac troponin I(cTnI),creatine kinase-MB(CK-MB) and cardiac function,and to observe the relationship with histological findings in rat with experimental autoimmune myocarditis (EAM).Methods Twelve Lewis rats were induced into control group by injection complete Freund's adjuvant; other twelve Lewis rats were induced into EAM by immunization with cardiac myosin.On the 21th day,cardiac function was evaluated by animal echocardiography,at the same day,we examined the changes of the cTnI,CK-MB and NT-proBNP and histological findings,score micro and macrohistological changes.Results Compared to the control group,the EAM rats had a significantly lower left ventricular ejection fraction [ (65.8 ± 4.4) ％ vs (86.9 ± 1.1 ) ％,P ＜ 0.05 ] and a larger left ventricular endsystolic diameter [ (3.88 ± 0.29) mm vs ( 3.16 ± 0.08 ) mm,P ＜ 0.05 ],and higher cTnI,CK-MB and NT-proBNP [ ( 392 ± 120) IU/L vs ( 1357 ± 397 ) IU/L,(6.8 ± 1.8) μg/L vs ( 17.2 ± 5.3 ) μg/L,( 110 ± 46) ng/L vs (706 ±218) ng/L,P ＜ 0.05 ].CK-MB was not correlated with histological changes (P ＜ 0.05).cTnI was correlated with microhistological changes ( P ＜ 0.05 ).NT-proBNP was correlated with macrohistological changes ( P ＜ 0.05 ).Conclusion NT-proBNP may be a prognostic marker of macrohistological changes and cTnI may be a prognostic marker of microhistological changes in autoimmune myocarditis.