Differences in patient classification of myocardial injury between high-sensitivity cardiac troponin (hs-cTn) assays have largely been attributed to assay design and analytical sensitivity aspects . Our objective was to compare Ortho Clinical Diagnostics ’ (OCD) hs-cTnI assay to OCD ’ s contemporary/conventional assay (cTnI ES) and another hs-cTnI assay (Abbott hs-cTnI) in samples obtained from different emergency departments (EDs). Two different sample types were evaluated (lithium heparin and ethylenediaminetetraacetic acid (EDTA) plasma) in a non-selected ED population (study 1, n = 469 samples) and in patients for which ED physicians ordered cardiac troponin testing (study 2, n = 1147 samples), from five different EDs . The incidence of injury in study 1 was higher with the OCD hs-cTnI assay (30.9% ; 95% CI : 26.9 to 35.2) compared to that of the Abbott hs-cTnI (17.3% ; 95% CI : 14.1 to 21.0) and the OCD cTnI ES (15.4% ; 95% CI : 12.4 to 18.9) assays, with repeat testing identifying 4.8% (95% CI : 3.0 to 7.5) of the OCD hs-cTnI results with poor reproducibility . In study 2 , 4.6% (95% CI : 3.5 to 6.0) of the results were not reported for the OCD hs-cTnI assay (i.e., poor reproducibility) with 12.7% (95% CI : 8.7 to 17.8) of the OCD hs-cTnI results positive for injury being negative for injury with the Abbott hs-cTnI assay . In summary, the OCD hs-cTnI assay yields higher rates of biochemical injury with a higher rate of poor reproducible results in different ED populations.