Primary cardiac lymphoma (PCL) is an extranodal non-Hodgkin's lymphoma exclusively located in the heart and/or pericardium. It is rare in immunocompetent patients and represents 1.3% of primary cardiac tumors and 0.5% of extranodal lymphomas. The clinical behavior is aggressive and the early symptoms are cardiac failure, syncope, arrhythmia, or pericardial effusion. Although echocardiography, computed tomography (CT) scan, magnetic resonance image (MRI) are the mainly used imaging techniques to detect cardiac tumors, pathologic examination is always required to confirm the diagnosis. Diagnosis of PCL is difficult due to non-specific clinical manifestations and requires invasive approach to get histopathologic evidence. While surgery with systemic chemotherapy or in combination with irradiation has been attempted, the only effective treatment is chemotherapy. However, the prognosis remains poor. We report on a 42-year-old woman who is diagnosed histopathologically as PCL by cardiac catheterization assisted percutaneous endomyocardial biopsy and treated successfully by anthracycline based chemotherapy.