Background <p>Epicardial cyst is an extremely rare congenital cyst. It is a congenital mesothelial cyst inside the pericardial sac in direct attachment to the epicardium of the heart and the roots of the great vessels.</p> Case presentation <p>A 15-year-old boy presented with palpitation and dyspnea on exertion of 2&#xa0;months’ duration. Transthoracic echocardiography (TTE) showed the presence of a cystic lesion in the right atrioventricular groove near the origin of the right coronary artery (RCA). Computed tomography (CT) scan of the chest with contrast, CT three-dimensional reconstruction image, and CT coronary arteriography confirmed the presence of a large ovoid cyst (6 × 4 × 4&#xa0;cm) in the right AV groove splaying it and stretching the proximal to mid-course of the RCA over the wall of the cyst without significant caliber attenuation of the RCA. Successful resection of the cyst with sparing of the RCA was done through the standard median sternotomy without the need for using the standby cardiopulmonary bypass (CPB). The postoperative course was uneventful, and the patient was discharged home on the postoperative day 6. Histopathological examination confirmed the diagnosis of an epicardial cyst with a lumen lined by flattened mesothelial cells.</p> Conclusions <p>Echocardiography is an essential tool for early diagnosis for patients complaining of unexplained cardiac symptoms. Multimodality imaging is needed for preoperative diagnosis and decision making for the management of the epicardial cyst. Epicardial cystectomy can be done safely without CPB even if the cyst is in direct relation to the coronary vessels.</p>