Herein we present a case of a right ventricular (RV) thrombus in a patient with arrhythmogenic cardiomyopathy (ACM). The 24-year old female patient was diagnosed with ACM after echocardiography and cardiac magnetic resonance imaging. Interestingly, at echocardiography, an unusal thrombus formation was detected at RV lateral wall. Also, CMR confirmed the thrombus and oral anticoagulant therapy was started. Even in arrhythmogenic right ventricular cardiomyopathy patients thrombi are rarely reported. However, the development of imaging techniques may enable more frequent detection and effective treatment of thrombi in these patients.