RESUMEN
We show two cases of transposition of the great arteries with arterioventricular discordance and aorta at both sides (right and left). They were diagnosed by angiocardiography and verified afterwards in the anatomical analysis of the specimens. We discuss the necessary steps taken for the diagnosis in which we followed De la Cruz's rules. We emphasize that this anatomical group should be distinguished from the group of arterioventricular concordance. Both groups have the same connection. Against the opinions of other authors, we think that this connection signifies only the same physiology in both groups, but not the same anatomy. This anatomy would be originated by a different embriological fact (different spatial location of the truncal and conal ridges).