Sudden cardiac death in well-trained athletes is most often superimposed on the presence of structural heart disease. However, some athletes die suddenly in the absence of overt heart disease. To improve identification of athletes at high risk for ventricular tachycardia (VT), ventricular repolarization, the signal-averaged electrocardiogram (ECG), and the echocardiogram from 13 male athletes with symptomatic VT and without evidence of manifest cardiac disease were compared with data obtained in 3 matched control groups (15 apparently healthy professional road cyclists, 10 professional basketball players, and 15 normal control subjects without any sports activity). All patients had apparently normal QRS duration on the routine ECG, and none were taking antiarrhythmic drugs. Echocardiography and signal-averaged electrocardiography were useful in distinguishing the group of athletes with tachyarrhythmias from the group of normal nonsporting controls, but not from both groups of normal athletes. The QT interval (V4) and the QT interval corrected with the cubic root were shorter for the nonsporting controls. Three parameters for QT dispersion showed significant differences (p < 0.003) between athletes with disease and all other groups. It is concluded that although significant differences were detected between normal subjects and the 3 groups of athletes by routine ECG, the signal-averaged ECG, and echocardiography, only an increased QT dispersion from the 12-lead ECG was helpful in distinguishing athletes with VT from other athletes.