Primary cardiac lymphoma is defined as a lymphoma of the heart and pericardium with little or no extracardiac or local involvement such as mediastinal lymph nodes or pleural effusion. Most cases are diagnosed only post mortem (1). If this disease could be diagnosed earlier, therapy with chlorpropamide, doxorubicin, vincristine and prednisone (CHOP) could bring about a remission (2,3,4). Transoesophageal echocardiography with three-dimensional acquisition is a new technique which can allow earlier diagnosis, and facilitate guided transvenous biopsy (5,6). We here report an example of the pre-mortem diagnosis of cardiac lymphoma by these techniques.