A 63-year-old woman was admitted to hospital with the chief complaint of new onset chest discomfort and pretibial pitting edema. Transthoracic echocardiography revealed a large invasive tumor on the heart protruding into the right atrium and right ventricle, which obstructed the outflow tract. She underwent transvenous 9Fr, 9-MHz ultra intracardiac echocardiography (ICE) (EP Technologies, Boston Scientific Corporation, San Jose, CA, USA) guided biopsy, and a diagnosis of malignant lymphoma was established from the specimen obtained. ICE-guided cardiac tumor biopsy may be one of the most useful strategies for diagnosis of cardiac tumors.