Pre-partecipation ECG screening of large populations has a significant socioeconomic impact. Technological progress now allows for high-tech-low-cost ECG screening using validated smartphone-based devices capable of guiding to the correct performance of a 12‑lead ECG by layman with no medical background. We enrolled 728 (364, 52% males) individuals, aged 12–13 years who underwent ECG screening with a smartphone 12‑lead ECG during school hours by layman volunteers. Correct electrodes placement was provided by a validated image-processing algorithm by the smartphone camera in the App. ECG interpretation was via a telecardiology platform and alterations classified following current standards. A total of 741 ECGs were recorded, of which 13(2%) were technically not interpretable. Mean PR, QRS and QTc were: 145 ± 22, 85 ± 19 and 387 ± 57 msec. No QTc prolongation was observed. Mean QRS axis was 15°; 26 (4%) patients presented an iRBB. T-wave inversion from V1-V3 was present in 145 (21%) subjects. Twenty-one(3%) patients were referred to second level examination: deep Q-waves in inferior leads in 12(1.6%), ventricular ectopics in 5(0.7%), anterior T-waves inversions V1-V4 in 3(0.4%); extreme right axis deviation in 1(0.3%). Second line investigations did not provide any definitive diagnosis. Total project costs (material equipment and human cost) was 14.460€, 19.51€ per individual. The potential net saving with respect to current pre-participation screening cost was 19%. Layman 12‑lead Smartphone-ECG population screening proved feasible and effective, with a rate of non-interpretable ECG of <5%. Potential cost-saving in ECG screening and recording was 19%, providing an appealing opportunity when large campaigns should be addressed also in developing countries. •Pre-partecipation ECG screening of large populations has significant socioeconomic impact. Technological progress allows for high-tech-low-cost ECG screening using smartphone-based devices capable of guiding a user with no medical background to perform a12-lead ECG.•We enrolled 728 (364, 52% males) individuals, aged 12–13 years who underwent ECG screening with a smartphone 12-lead ECG during school hours by layman volunteers.•Twenty-one(3%) patients were referred to second level examination, reasons were: deep Q-waves in inferior leads in 12(1.6%), ventricular ectopics in 5(0.7%), anterior T-waves inversions V1-V4 in 3(0.4%); extreme right axis deviation in 1(0.3%).•Total project costs was 14.460€, 19.51€ per individual. The potential net saving with respect to current pre-participation screening cost in ECG recording and interpretation was 19%.