This report describes the echocardiographic appearance of an intrapericardial mass and pericardial effusion in an otherwise healthy patient. The tumor was a globular mass attached to the left atrium by a stalk, suggestive of a myxoma. The mass was successfully excised and the patient had an uneventful recovery. Histology revealed a smooth muscle tumor with extensive adipocytic differentiation and numerous small blood vessels. This study represents the first echocardiographic description of a smooth muscle tumor presenting as an extracardiac myxoma.