A 66-year-old male referred to our hospital with dyspnea and bilateral lower-extremity edema. Chest radiography (CXR) showed pleural effusions and cardiomegaly. Transthoracic echocardiography revealed large pericardial effusion with a heterogeneous hyperechoic mass in the right ventricular pericardial wall. Histopathological examination confirmed the diagnosis of epithelioid mesothelioma. Primary pericardial mesothelioma is an extremely rare and poorly diagnosed malignancy with a historically poor prognosis. Thus, a timely diagnosis and treatment are crucial for the management of primary pericardial mesothelioma.