Objective To investigate the value of cardiac troponin Ⅰ (cTn Ⅰ) in diagnosis of multi-trauma patients combined with myocardiac contusion.Methods A retrospective review was made on 98 cases of multi-trauma patients combined with blunt chest trauma.The groups were identified according to whether the patients were associated with myocardiac contusion or not,including myocardiac contusion group (n =48) and non-myocardiac contusion group (n =50).The detection and diagnosis of myocardiac contusion in the use of different cut-off points of cTn Ⅰ and creatine kinase MB isoenzyme/creatine kinase (CKMB/CK) or their combination were compared between groups.Results cTn Ⅰ ≥0.60 ng/ml had a specificity of 90.0％,a sensitivity of 64.6％ and a Youden index of 0.54 in diagnosis of myocardiac contusion,indicating a best diagnostic accuracy as a single parameter.As compared with the single use of cTn Ⅰ ≥ 0.60 ng/ml or CKMB/CK ≥ 6％ in diagnosis of myocardiac contusion,the combined use of two parameters presented a significantly higher diagnostic sensitivity (85.4％ vs 64.6％ ; 85.4％ vs 27.1％ respectively,both P ＜ 0.05),but no markedly lower specificity (84.0％ vs 90.0％ ; 84.0％ vs 88.0％ respectively,both P ＞0.05).cTn Ⅰ level was positively correlated with ISS score of the multi-trauma patients combined with myocardiac contusion (r =0.534,P ＜ 0.01).Mortality rate in patients with severely increased cTn Ⅰ was much higher than that in patients with mild-moderately increased cTn Ⅰ (P ＜ 0.01).Conclusions cTn Ⅰ ≥0.60 ng/ml presents a high sensitivity and preferable specificity for diagnosis of multiple trauma patients combined with myocardiac contusion.It can be served as a biomarker for diagnosis of MC and its combination with CKMB/CK≥6％ improves the diagnostic sensitivity.cTn Ⅰ can be used as an assessment indicator for the early risk stratification and outcome in multi-trauma patients combined with myocardiac contusion.