Real-time 2-dimensional (2-D) echocardiograms were performed in 4 patients, all with considerable obstruction within the right ventricular (RV) body, in 3 patients due to muscle bundles and in 1 due to hypertrophic cardiomyopathy (HC). None had obstruction at the pulmonic valve level or immediately below. Echocardiographically, obstruction presented in 3 patients as localized bulging of the RV free wall in the subinfundibular region such that the RV cavity presented a typical "hourglass" appearance. Associated ventricular septal defect (VSD) was detected in 2 patients by echocardiography. In the fourth case, a patient with HC, RV obstruction was associated with a prominent bulge of the ventricular septum into the right ventricle. In 3 patients, the obstruction was convincingly demonstrated only in the subcostal RV inflow-apex-outflow plane, rather than in the standard echocardiographic planes. Pulse Doppler studies in 2 patients demonstrated disturbed RV flow. Obstruction within the RV body is a potentially serious condition which has been overlooked both at cardiac catheterization and at surgery. Demonstration of this lesion by 2-D echocardiography appears feasible and would greatly improve diagnostic accuracy. © 1983.