Primary cardiac lymphoma defined as involving only the heart and pericardium, is very rare and is diagnosed predominantly late in the course of illness or autopsy. This tumor is commonly fatal and until recently were rarely diagnosed antemortem. Recently, it was reported in patients with acquired immunodeficiency syndrome. We report a case of primary cardiac lymphoma in a 56 year old female who showed progressive exertional dyspnea. On echocardiogram and CT scan, large ill defined mass was demonstrated in right atrial and ventricular wall. It was diagnosed as B-cell type lymphoma on open cardiac biopsy.