Background: The European Society of Cardiology recommends cardiovascular screening to competitive athletes. In young population the execution of 12-lead ECG screening is still controversial. Purpose: The aim of our study is to evaluate the distribution of ECG abnormalities between competitive athletes, non competitive athletes and non athletes. Methods: We evaluated prospectively 14862 high school students (age17.2±2.4 years old; 45.9%male): 5653 (38.04%) non athletes (G-A), 6155 (41.42%) non competitive athletes (G-B) and 3052 (20.54%) competitive athletes (G-C). They were screened using 12-lead ECG. The statistical difference was considered significant only for p-value ≤0.05. Results: We found a significant statistical difference between distributions of ECG abnormalities in three groups, particularly Brugada like ECG pattern, premature ventricular contraction, left atrial enlargement are more common in G-A then in the other groups. No significant statistical difference was found for the other abnormal ECG findings. ... Conclusions: Our results evidence that the distribution of ECG abnormalities between three groups is similar or higher in non athletes group. Non athletes have high rate of abnormal ECG; this suggest that an ECG screening is recommended also in non athletes.