OBJECTIVES: To estimate the cost-effectiveness of delayed troponin testing for myocardial infarction (MI), as recommended in current guidelines, compared to troponin testing and other biomarkers 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. Sensitivity and specificity of the strategies were estimated by meta-analysis of diagnostic cohort studies of presentation  troponin T. The risk of reinfarction and death (with and without treatment) was determined using data from a study by Mills et al, Lifetime QALYs were estimated from life expectancy and corresponding annual utilities. The discounted life expectancy of patients with MI and MI with reinfarction was estimated from Polanczyk et al, while the utility of patients with MI was estimated from Ward et al. 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. 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.