Background : Acute cellular rejection determines the clinical outcomes of heart transplantation (HTPL). Endomyocardial biopsy (EMB) is the standard method to diagnosis of acute rejection. However, it is invasive and may cause some complications and sometimes suboptimal results. And no biomarker is available to predict cellular rejection clinically. Recently, several sensitive cardiac troponin assays were validated as very sensitive markers for early diagnosis of myocardial infarction. These assays may be valuable to diagnose acute rejection in HTPL patients. Method: We conducted a single center cross-sectional study comparing the conventional Troponin T and Roche Elecsys짰 high-sensitive Troponin T and Simens Troponin I Ultra levels according to the rejection grades diagnosed by EMB. The blood samples obtained from patients who were received HTPL and performed the routine EMB to monitor the acute rejection. The final diagnosis for acute rejection (pathologically, grade 2R or more by revised, 2004 ISHLT classification) was determined by two cardiologists and one pathologist. We evaluated of predictive value of Roche high-sensitive Troponin T and Simens Troponin I ultra levels in patients with acute rejection whether their levels correlate to grade of acute rejection. We considered to make the cut-off point of their levels which need some immunosuppressive therapy in acute rejection by use of ROC curve. Results: We evaluated 128 patients who were received HTPL and performed the routine EMB. Biopsy results of 113 patients were grade 1R or less which defined non rejection group and 15 patients were grade 2R or more which defined rejection group. Conventional Troponin T and Roche high-sensitive Troponin T and Simens Troponin I ultra were positive linear correlation to each others. (Conventional Troponin T and Roche high-sensitive Troponin T; r=0.869, Conventional Troponin T and Simens Troponin I ultra ; r=0.496, Roche high-sensitive Troponin T and Simens Troponin I ultra; r = 0.641, all p-value < 0.001) However, These assays did not show difference between acute rejection group and non rejection group. (Conventional Troponin T : 0.259짹0.607 vs 0.067짹0.170, p=0.687, Simens Troponin I ultra : 0.296짹0.607 vs 0.078짹0.200, p=0.548, Roche high-sensitive Troponin T : 0.276짹0.645 vs 0.076짹0.161, p = 0.926, respectively) Conclusion: Conventional Troponin T and Roche high-sensitive Troponin T and Simens Troponin I ultra were positive correlation to each others. but they can not be used predictive marker for diagnosis of acute rejection and not substitute for EMB. Key words : Acute rejection, Tropoin, Heart transplantation (HTPL), Endomyocardial biopsy(EMB)