In 1875 Rokitansky first described corrected transposition of the great vessels. Harris and Farber (1939) and Cardell (1956) thought that since inversion might occur in any part of the cardiac tube, in theory any one of eight types of transposition could result (Fig. 1). In their groups A3 and A4 the aorta arises from the morphological left ventricle but receives unoxygenated blood, hence they regarded it as being "corrected" anatomically but not physiologically. Their groups Bl and B2 associated with bulbus inversion, and sinu-atrial and ventricular inversion respectively, show both physiological and anatomical correction, the aorta arising from the morphological left ventricle and receiving oxygenated blood. In B3 and B4 associated with bulbo-ventricular inversion, and sinu-atrial inversion respectively, the aorta arises from the morphological right ventricle but receives oxygenated blood, hence it is corrected physiologically but not anatomically. Cardell (1956) and Harley (1958) suggested that the term corrected transposition should be confined to those cases with physiological correction only. Recent papers on the subject tend to confine the words "corrected transposition" to one anatomical type, i.e. the one associated with bulbo-ventricular inversion (Cardell's B3). Several papers have included cases of single ventricle among their material. The presence of a single ventricle vitiates any discussion of whether the transposition present is corrected or not, since mixing of the arterial and venous blood occurs in the common chamber. Several definitions have been given for corrected transposition, but we propose to use the term simply to define the condition where the transposed aorta receives oxygenated blood, and the transposed pulmonary artery receives venous blood. This paper is presented to describe three different types of corrected transposition that are readily recognizable whether there is lxvocardia or dextrocardia. Inversion means a reversal of the lateral relation between structures in the frontal plane. Complete transposition of the great vessels means that the aorta is lying anterior and to the right of the pulmonary artery, with livocardia. Inverted-transposition of the great vessels is used in the sense of Spitzer (1923) where the aorta is lying anterior and to the left of the pulmonary artery, with levocardia. During the course of the discussion cases of dextrocardia and levocardia will be mentioned. In order that these anomalies shall be properly understood, there should be a frame of reference which is that of normality, to which the abnormal situation may be compared in terms of inversion or transposition. The normal dextroposed heart in dextrocardia with situs inversus, with the venous chambers to the patient's left, is a mirror image of the normal lhvoposed heart in situs solitus. If in dextrocardia, the venous atrium is on the patient's right and the arterial on the left, they are by our definition inverted. This point is emphasized because this definition differs from that of Mande...