We observed 15 patients with arrhythmogenic right ventricular dysplasia (ARVD): 9 with definite and 5 with probable ARVD (modified European Criteria, 2010). Eight patients had typical ARVD (frequent right ventricular extrasystoles, nonsustained right ventricular tachycardia without heart failure with or without myocarditis). Five patients had ARVD with progressive heart failure (right- or biventricular with or without myocarditis). Two patients had full scale arrhythmic form (sustained right ventricular tachycardia without or with right ventricular dilation, with or without myocarditis). In 3 cases diagnosis was confirmed morphologically or with DNA-diagnostics. This material allowed us to highlight the following specific points related to diagnostics of ARVD. Detection of fat at MRT is not obligatory for diagnosis, fat can be detected by MSCT; ventricular arrhythmias can move backwards in the picture of the disease; leading clinical manifestation can be unexplained right ventricular insufficiency; ARVD can be combined with other genetic cardiomyopathies as well as with infectious immune myocarditis (up to 50% of patients); elevated titer of anticardiac antibodies is not characteristic for isolated ARVD; myocardial biopsy allows to verify both ARVD and concomitant myocarditis. The paper also contains discussion of the role of myocarditis in various forms of ARVD and possibilities of its diagnosis and treatments.