Authors present the results of angiocardiographic study on 30 patients with complete A-V canal. This study is divided in two parts: First, they define general concepts such as aortic suspension, anterior common valve-theoretical right border angle, left and right regurgitation, etc. Secondly, they classify A-V canal in two groups according to the following characteristics: 1) Anterior common valve normal, moderate suspension of the aorta less than 50%, rough right border of the left ventricle, angulation less than 45 degrees, medial interventricular communication and left regurgitation. 2) Common anterior valve small, important suspension of the aorta greater than or equal to 50%, smooth right border, angulation greater than or equal to 45 degrees, large communication and left and right regurgitation. Differential data between interventricular communication and valvular regurgitation are commented. They emphasize how important the posterior smooth septum and the common anterior valve are in producing the suspension of the aorta and also in the narrowing and elongation of the infundibulum. Finally, some considerations about the surgical implications according to the type of canal are made.