The value of imaging techniques such as transthoracic echocardiography, angiography and magnetic resonance imaging in the diagnosis of arrhythmogenic right ventricular dysplasia-cardiomyopathy (ARVD) is limited. First experiences with intracardiac ultrasound have been made during electrophysiological interventions. The ability of using intracardiac ultrasound in ARVD should be tested. In 25 patients with IFSC/ESC criteria of ARVD (nine males, 16 females) with a mean age of 54 (29-78) years suffering from sustained ventricular tachycardia in three cases, positive family history in four cases and syncopes in six cases intracardiac ultrasound was done using 6 French (Fr) 12.5 MHz catheters and the CLEAR VIEW ULTRA Intravascular System (Boston Scientific). Images were taken from the right ventricular apex, outflow tract and infundibulum. Results were compared to selective right ventricular angiography. Right ventricular (RV) angiography revealed bulges and a partial or complete loss of trabecular structure in 22 cases at the apex, in 13 cases at the infundibulum and in 14 cases at the right ventricular outflow tract. Intracardiac echocardiography was able to demonstrate sacculations in all patients at the apex, in 20 cases at the infundibulum and in 16 patients at the right ventricular outflow tract. Sacculations in all segments of the right ventricle were based on a partial or complete loss of trabecular structure. A whole of 36 segments presented with wall thinning (<3 mm) and 15 segments with normal wall structure and wall thickening of surrounding myocardium (>4 mm). In 26 segments the structure of right ventricular wall was inhomogeneous. In comparison to angiography as the 'gold standard' intracardiac ultrasound presented with additional details in 12 cases and the demonstration of angiographic misinterpretation in one case. Intracardiac ultrasound in ARVD is feasible in all cases with 6 Fr 12.5 MHz catheters and provides additional information to the angiographic phenomenon of bulges and to the aspect of tissue characterisation.