Arrhythmogenic right ventricular dysplasia (ARVD), disease of uncertain etiology, is characterized by fibrofatty collections in the right ventricular myocardium, premature ventricular complexes with left bundle branch block (LBBB) morphology, ventricular tachycardia and fibrillation.To point out diagnostic methods for this progressive disease and to analyze differential diagnosis and significance of arrhythmogenic right ventricular dysplasia in young, active athletes.Arrhythmogenic right ventricular disease can be asymptomatic or manifested (syncope). It is not uncommon that the first evidence of the disease is ventricular tachycardia/fibrillation or sudden cardiac death. Results of electrocardiography, echocardiography, invasive and other methods can, even after few years, be negative for ARVD. The most significant ECG features are inverese T wave in precordial V1-V3 leads and widened QRS complex (> 120 ms) in V1 lead. Significant echocardiographic features and data obtained by invasive hemodynamic examinations are: dilated right ventricle, left and right ventricular end-diastolic diameter ratio less then 0.5, hypokinetic/akinetic areas involving the wall of the right ventricle, predominantly inferobasal, apical and wall of the left ventricular outflow tract. Findings may also include deep fissures among hypertrophied trabeculae. Biopsy may reveal fibrofatty tissue in hypo/akinetic regions of the right ventricular myocardium.Since arrhythmogenic right ventricular dysplasia is diagnosed in predominantly young population, not uncommonly athletes, and since it may be cause of sudden cardiac death, there must be a high degree of suspicion in cases with activity related VT/VF and positive family history (it is proposed that it is a hereditary disease).