Abstract: Objective: To evaluate the clinical significance of cardiac troponin I （TnI） measurements with radial partition immunoassay.Methods: Of the cases （n=100） studied, 60 were healthy adult blood donor,30 had the elevations of total creatine kinase （CK） and 10 had acute myocardial infarction The cases were evaluated clinically by ECG TnI and CK MB were determined with specific monoclonal monoclonal sandwich assay by Deda Stratus II analyzer.Results: The 95% upper reference limit was 0.8μg/L of TnI in the healthy adult blood donor Among the cases with elevations of CK, six patients had elevation of CK MB,but none had increased TnI The levels of TnI were elevated only in 10 patients with acute myocardial infarction In these cases TnI levels rose above the reference range within 3～6 hours, the peak value in 12～24 hours, and remaining elevated in 8 cases for 168 hours following the onset of chest pain.Conclusion: Cardiac TnI is a highly specific biochemical marker for myocardial injury The measurement of TnI should facilitate distinguishing whether elevations of CK are due to myocardial or skeletal muscle injury