Primary cardiac lymphomas (PCLs), involving solely heart and/or pericardium at presentation, are rare events. They are frequently recognized at autopsy and generally carry a poor prognosis due either to a delay in the diagnosis or to infiltration of heart structures. We report here on two patients with large B-cell PCL. One is a 52-year-old man who presented with multiple cardiac tumors infiltrating mainly the right atrium and the inter-atrial septum. Diagnosis was established by ultrasound-assisted transesophageal biopsy of the intra-atrial multilobated tumor mass. He was treated with Rituximab-implemented high-dose sequential (R-HDS) chemotherapy followed by autologous peripheral blood stem cell transplantation, attaining complete response. He had no evidence of disease 24 months from onset. The second patient was a 70-year-old woman who presented with pericardial tamponade and low-output cardiac failure. Despite prompt pericadiocentesis and chemotherapy with cyclophosphamide and vincristine, she died 2 weeks later. Postmortem examination revealed large B-cell lymphoma proliferation confined to the heart. Whether primitive heart localizations represent an independent prognostic factor, and what specific measures should be adopted in patients with this rare presentation is the subject of the present report and review of the literature.