Athlete’s heart is a non-pathological condition commonly in athletes econdary to routinely exercise, which may be associated with other serious medical conditions and severe cardiovascular events such arrhythmias. Objective: to evaluate the QT/QTc interval dispersion in adolescent athletes regarding on the type of physical effort. Methods. Subjects: 51 sporting teenagers (14-17 years old) organized in 2 lots. First lot: 25 endurance-trained athletes (runners, football-players) and the 2nd lot: 26 strength-trained athletes (wrestlers, boxers). Control lot: 20 teenagers in the same age group, without any sign of cardiac suffering. ECGs were assessed on all the patients, athletes and non-athletes and used to calculate QT interval in three successive cardiac ECG cycles, the QT interval dispersion (QTD) (the difference between maximum and minimum value of QT interval) and the QTc interval dispersion (QTcD)(Bazzet’s formula). Results the average values of QTD and QTcD in the 1st and 2nd group were superior than the values in the control group but the difference is not statistic significant. I lot=QTD: 43.54±21,03msec; QTcD: 50.81±19.34msec; II lot =QTD: 48.23±12.56msec; QTcD: 53.59±17.21msec; control lot=QTD: 35.88±10.22msec; QTcD: 39.23±14.81msec. The highest values of QT interval were found in strength-trained sporting teenagers. The highest values of QTD and QTcD were found in sporting teenagers from the second lot that it might be possible to have a higher ventricular arrhythmia risk. There wasn’t any case with QT interval value longer than the normal. Conclusions. At side of other parameters ECG, it is useful research screening of the QT interval and QTc interval dispersion during periodic controls, like indicator of the risk of the ventricular arrhythmias at sporting teenagers.