TO OUR knowledge, this is the first report of echocardiographically studied rhabdomyosarcoma of the heart. Square-wave paradoxical septal motion was noted. In the absence of previously reported causes of paradoxical septal motion, right ventricular tumor appears to be a newly recognized cause of paradoxical septal motion. Report of a Case A normotensive 59-year-old woman with a long history of spastic colon symptoms was admitted during a bout of near syncope. A presystolic "seagull" murmur at the lower part of the left sternal border and elevated jugular venous pressure, both of which increased on inspiration, an early systolic ejection murmur, which decreased with inspiration, a prominent jugular A wave, and a normal second heart sound were demonstrated (Fig 1). There was mild peripheral cyanosis. Electrocardiographic axis was +120°, with tall R waves in right precordial leads and a QRS complex duration of 0.10 seconds, while an electrocardiogram eight months earlier was