AIMS: Despite the increased prevalence of atrial fibrillation (AF), data for the implementation of nationwide screening programmes are limited. The aim of this national screening study was to increase nationwide awareness about AF and stroke risk, to determine the prevalence of AF in Belgian general population using an ECG handheld machine and its feasibility to identify new AF cases. METHODS AND RESULTS: We analysed data obtained from 5 years of the 'Belgian Heart Rhythm Week' screening programme. All subjects were screened using a one-lead ECG handheld machine. Among 65 747 subjects screened, AF was recorded in 911, with an overall prevalence of 1.4% [95% confidence interval (CI) 1.2-1.6%]. High thrombo-embolic risk, as assessed by CHA2DS2-VASc score ≥2, was recorded in 69% of AF subjects. In subjects with high thrombo-embolic risk, only 5.4% were treated with oral anticoagulant (OAC) and 5.8% were treated with OAC and antiplatelet drugs. Among recorded AF cases, the use of the ECG handheld machine allowed identification of 603 new AF patients (1.1%, 95% CI 0.9-1.3%). Factors associated with incident AF were chronic heart failure (P < 0.001), age (P < 0.001), diabetes mellitus (P < 0.001), previous stroke (P < 0.001), vascular disease (P < 0.001), and male sex (P < 0.001). CONCLUSION: In this Belgian national screening programme, prevalence of AF was 1.4%. The use of an ECG handheld machine is feasible to identify a significant number of new AF cases, most with a high thrombo-embolic risk. Given the low OAC use recorded, greater efforts in AF detection and treatment are urgently needed to reduce the burden of stroke associated with this common arrhythmia.