A man aged 50 presented with a history of a cerebrovascular accident and arterial embolism at two discrete peripheral sites. Echocardiography showed thrombus trapped in an interatrial site and impending paradoxical embolism was diagnosed. Treatment with heparin was started and the potentially embolic intracardiac material was removed at open heart surgery. The patient was treated with warfarin and made a good recovery. This is only the third case report of impending paradoxical embolism diagnosed in life.