BACKGROUND: We assessed the utilization rationale behind provider ordering of cardiac troponin I (cTnI) testing for the diagnosis of myocardial infarction after implementation of a hospital-wide serial order protocol. METHODS: During 2 months in 2013, any request for additional cTnI testing within 30 days of the initial serial cTnI order prompted an electronic health record best practice alert (BPA), which included clinical decision support that could be bypassed by giving a clinical indication. cTnI orders were not limited (timing, number), and upon BPA, trigger data was collected for clinical indications and actions, patient stay (duration, location), International Classification of Diseases, Revision 9 diagnosis, cTnI orders, and timing of cTnI measurements. RESULTS: The BPA was triggered 1477 times by 423 providers who cared for 702 patients. There were a mean of 3.6 cTnI results per patient, 2.1 BPAs per patient, and 1.2 visits per patient. Providers (42% of whom were residents) acknowledged and overrode the BPA 97% of the time. In response to the BPA, 65% of providers selected a prepared rationale: 64% acute coronary syndrome/ST-elevation myocardial infarction/non-ST-elevation myocardial infarction; 30% demand ischemia; and 6% non-ACS myocardial necrosis. Of the remaining 35% of providers, 71% listed no rationale for their additional cTnI orders. Of patients with a BPA, 93% had non-ACS-related primary International Classification of Diseases, Revision 9 diagnosis, and 58% of the time, patients' cTnI results never increased during their stay. In 53% of cases, BPAs were generated by a request for an additional cTnI series when <2 results were available. CONCLUSIONS: Providers largely ignored the BPA that warned of potential overutilization of cTnI testing independent of diagnosis, including ACS.