We report an unusual case of a 61-year-old woman with right atrial primary cardiac lymphoma extending into the right jugular vein through the superior vena cava. A transoesophageal echocardiographic study revealed the presence of a large mass occupying four fifths of the right atrial cavity and invading the superior vena cava, which appeared almost completely occluded. These findings were confirmed by computed tomography scan and magnetic resonance imaging. At autopsy, a large (7 x 3 cm) whitish ovoid mass with multiple nodules was found in the right atrium and superior vena cava. Histopathological examination revealed a monotonous population of lymphoid B-cells.