Aims Atrial fibrillation (AF) is the most common arrhythmia and prevalence increases with age. Patients with AF have a high risk of stroke, and screening for AF is recommended in all people aged 65 years or older to identify patients eligible for stroke prevention. A handheld, single-lead electrocardiogram (ECG) device can be used for systematic screening in the population at risk. The objective of this study is to estimate the cost-effectiveness of screening for AF in primary care with the MyDiagnostick (R) during seasonal influenza vaccination in the Netherlands. Methods and results Lifetime costs and effects of a single screening session for AF detection were assessed from a societal perspective with a decision analytic model consisting of a straightforward decision tree and a joining Markov model. The decision model simulated all patients aged 65 years and over attending the seasonal influenza vaccination in the Netherlands. Event probabilities were derived from clinical trials. Sensitivity analyses were performed to assess the impact of important model assumptions as well as determining the relative effect of individual parameters. Screening for AF with the MyDiagnostick (R) in all patients older than 65 years that attend seasonal influenza vaccination in the Netherlands would decrease the overall costs by (sic)764 and increase the quality-adjusted life-years (QALYs) by 0.27 years per patient. Early detection of AF would prevent strokes and leads to beneficial health effects with subsequent cost savings. This screening method would have an estimated probability of 99.8% for being cost-effective at a conservative willingness-to-pay of (sic)20 000/QALY. Conclusion Screening for AF in primary care with a handheld, single-lead ECG during seasonal influenza vaccination is very likely to be cost saving for identifying new cases of AF in the Dutch population aged 65 years and over. Active screening for AF with a single-lead, handheld ECG device during seasonal influenza vaccination could be implemented in primary ...