Abstract: Objective: To explore the diagnostic significance of detection of myocardial troponin I mRNA(cTnI-mRNA) in peripheral blood for dilated cardiomyopathy.Methods: Reverse transcriptase polymerase chain reaction(RT-PCR) method was employed to detect cTnI-mRNA from the peripheral blood and nucleated cells of 32 patients with dilated cardiomyopathy.The serum levels of creatine kinase,isoenzyme,aspartate aminotranferase,lactate dehydrogenase and cTnI were studied at the same time.One blood sample from a patient receiving heart transplant was examined pathologically and twenty other blood samples from blood station were collected as control.Results: Swell cardiac myocytes,mitochondrial rupture,severe vacancylike denatureation,nucleus abnormality and condensed chromatin borders were observed by electron microscopy.The RT-PCR was all negative from nucleated cells,while fourteen positive RT-PCR were detected from peripheral blood.In the control group,no positive results were found from either the nucleated cell or peripheral blood.Of the 32 patients,positive enzymology was detected in six cases,positive cTnI was detected in five and fourteen had positive RT-PCR.The positive rate of RT-PCR was significantly higher than that of enzymology and cTnI detection(P<0.05 and P<0.01).Conclusions: cTnI-mRNA is located in the serum after myocardial injury occurred.RT-PCR method is more sensitive than enzynology and cTnI detection in the diagnosis of dilated cardiomyopathy.