A 72-year-old Chinese man presented with mild symptoms of heart failure. Transthoracic echocardiography showed signs of cardiac tamponade though clinically he was relatively well. The option of pericardiocentesis was not carried out due to a narrow window for aspiration with only a thin layer of effusion seen surrounding the apex and right ventricle on subcostal view.Pericardial window was done via a left anterolateral thoracotomy. Intraoperatively, 500 cm3 of purulent fluid was drained. Microbiology screens were all negative. We present the atypical clinical course of this elderly man presenting with a large pyopericardium.