OBJECTIVES: To estimate the cost-effectiveness of delayed troponin testing for myocardial infarction (MI), as recommended in current guidelines, compared to troponin testing at presentation. METHODS: We developed a decision analytic model to estimate the cost-effectiveness of diagnostic strategies for MI, measured as the incremental cost per quality-adjusted life year (QALY) gained by each strategy compared to the next most effective alternative. The model was applied to a hypothetical population of 1000 patients attending hospital with symptoms suggesting MI but a normal or non-diagnostic electrocardiogram (ECG) and no major co-morbidities requiring hospital treatment. Delayed troponin testing (10-12 hours after symptom onset) was compared to standard and high sensitivity troponin testing at presentation and no testing. We tested three different scenarios regarding delayed testing, in relation to the delay between results being available and a decision being made, the “doctor on demand” scenario, in which medical staff were available 24 hours a day to make a disposition decision within one hour of the results being available, twice daily ward round and once daily ward round scenarios where medical staff were only available at twice daily ward rounds and once daily ward rounds, respectively. RESULTS: In all scenarios tested presentation high sensitivity troponin testing was the most effective strategy with an incremental cost-effectiveness ratio (ICER) below the £20,000/QALY threshold. Delayed troponin testing was only likely to be cost-effective if a discharge decision could be made as soon as a negative result was available and the £30,000/QALY threshold was used. CONCLUSIONS: Delayed troponin testing is unlikely to be cost-effective compared to high sensitivity troponin testing at presentation in most scenarios. The current guidelines recommending 10-12 hour troponin testing does not appear to promote cost-effective use of hospital resources, unless services are in place to allow rapid decision making once delayed test results are available.