Nine cases are reported of perimembranous ventricular septal defect associated with left ventricular to right atrial shunting. Cineangiographic findings included an aneurysm of the membranous septum in all patients; two patients had obvious adherence of deformed tricuspid valve leaflets to the membranous septum. The location of the ventricular septal defect was confirmed at surgery or cardiac endoscopy in seven patients. In the presence of a perimembranous ventricular septal defect, left ventricular to right atrial shunting is usually the result of tricuspid valve abnormalities, including clefts or perforations of the septal leaflet, deformity or adherence of valve tissue to the margins of the septal defect and widening of the anteroseptal commissure. Biplane left ventriculography, using the long axial oblique and reciprocal right anterior oblique projections, may best demonstrate the pathologic anatomy, although the hepatoclavicular projection is a useful alternative, particularly when an atrioventricular canal defect is a diagnostic consideration.