T HE FIRST descriptions of the trisomy-18 syndrome were in 1960 by Edwards,' Patau,2 and Smith3 and their associates. Although there was disagreement concerning which of the three pairs of chromosomes had an extra number, it now appears to be pair 18. The major malformations involve the skin, face, heart, and the central nervous, musculoskeletal, gastrointestinal, and urogenital systems. Overlapping digits (clinodactyly) and "rocker-bottom" feet are especially noteworthy.4-'6 Heretofore the major congenital cardiac anomaly reported in this syndrome was a defect in the interventricular septum. Patent ductus arteriosus, patent foramen ovale and, more rarely, atrial septal defect, a,tresia of the mitral valve, and bicuspid aortic or pulmonic valves, or both, have been noted. Gottlieb and associates17 reported two patients in whom the aorta was dextroposed and overrode the ventricular septal defect. Crawfurd18 further documented this association in a patient who had dextrocardia and in whom both great vessels originated from the right ventricle. It is the purpose of this paper to describe the cardiac findings in seven infants who had the trisomy-18 syndrome with a ventricular septal defect and origin of both great vessels from the right ventricle.