Diagnosis of the univentricular heart and recognition of its most important variations depends on the establishment of atrial situs, the demonstration of the type and mode of the atrio-ventricular connexion, the identification of the presence or absence of a rudimentary chamber, the establishment of its morphology, together with that of the main chamber, and classification of the arterial connexion. A logical means of demonstrating these features is presented, depending on bronchial visualization, one or possible two injections of contrast medium into the main chamber, followed if necessary by selective injection into the rudimentary chamber, and in exceptional cases, demonstration of the atrial septum by atrial injection. The advantagess of cranio-caudal tilt and oblique projections are discussed in detail.