constitutes j the roentgen study of the chambers £3 of the heart and associated great blood vessels during their opacification by an intravenously injected radiopaque solution. The procedure as it is known today was first successfully accomplished on Jan. 30, 1937 During recent years, many methods foi Automatic serial ioentgenographv have been employee to obtain piogressive visualizcltion of the contrast substance in its passage through the veins, the right heart, the pulmonary vessels, the left heart and the aorta. Speeds of up to twelve exposures a second in two projections simultaneously are a pr-actical reality6 although one oi two per second exposure frequencies are usually (liagnosticallv adequate. A commercially obtainable x-r-av roll-film magazine affords 9A inch square exposui-es at a fiequencv of li) to two films per second and has provedl to he a satisfactoi-y means of :ingiocari-(liogi-al)hi (lrecor(ling.7' NORMAL ANGIOCARDIOGRAX1 Angiocardiography has significantly added to the understanding of conventional chest roentgenography and fluoroscopy and has been of value in the teaching of radiology and anatomy.9 Its ability to provide a gross "dissection" of the heart and mediastinum during life is unique among the varied methods of cardiovascular study. Angiocardiography has provided confirmation of certain assumptions concerning the composition of the cardiac silhouette; it has dispelled other erroneous concepts. For example, While verifying the predominantly vascular composition of the normal hilar shadows, angiocardiography has shown conclusively that the pulmonary conus does not participate in the formation of the heart shadow in the frontal projection. Figure 1 illustrates the composition of the normal cardiac silhouette in