Wide-angle two-dimensional echocardiography was used to establish criteria for recognition of ventricular situs and ventricular morphology in 27 patients (ages 2 month to 58 years) with atrioventricular amd ventriculoarterial discordance (corrected transposition of the great arteries). The morphologic left ventricle was recognized by the presence of an atrioventricular valve that was attached more superiorly along the ventricular septum than the other atrioventricular valve, that had a fish-mouth (bicommissural) appearance in diastole, and that had two discrete papillary muscles; by a ventricle with a finely trabecular pattern and ellipsoid shape; and by the presence of direct continuity between the atrioventricular and semilunar valves. The morphologic right ventricle was recognized by the presence of an atrioventricular valve that was attached more inferiorly along the ventricular septum, that had a triangular (tricommissural) appearance, and that had multiple irregular papillary muscles; by a ventricle with a coarsely trabecular pattern and a triangular or crescentic shape, and by the presence of muscular atrioventricular-semilunar valve discontinuity. Using these criteria, ventricular situs and morphology could be reliably determined by noninvasive two-dimensional echocardiography. In addition, two-dimensional echocardiography allowed the recognition of frequently associated anomalies. In this series, two-dimensional echocardiography demonstrated Ebsteins's malformation of the left atrioventricular valve in four patients and a straddling atrioventricular valve in eight (one right-sided, seven left-sided.