OBJECTIVES: The aim of this study was to evaluate costs and benefits of diagnosing patients with syncope of unknown aetiology with implanted loop recorders compared to clinical practice (conventional investigation) of an electrophysiology, from the Spanish National Health System perspective. METHODS: Based on an economic decision analysis model, the cost-effectiveness study analyses diagnostic yield results from clinical practice versus Reveal DX®, with a time horizon of one year. Clinical data and resource use was obtained from a randomised controlled trial and expert opinion. Cost data was expressed in Euros 2010. A univariate sensitivity analysis was carried out to analyse the robustness of the model by modifying the number of outpatient visits, the costs and the diagnostic yield for both strategies. RESULTS: The incremental cost-effectiveness Ratio of Reveal DX® versus conventional investigation was €3167 per additional diagnosis, resulting in a confidence interval of 95% of the incremental cost-effectiveness ratio of €2335-€4867 per additional diagnosis made. The results of the univariate sensitivity analyses did not change the main results from our study. CONCLUSIONS: Reveal  DX® in the diagnosis of syncope of unknown aetiology after an initial evaluation is a cost-effective strategy compared to conventional diagnosis for the Spanish Health System, since it increases diagnostic yield at a reasonable incremental cost.