The lesion that, nowadays, is most usually described as “hypoplastic left heart syndrome”, was initially described in terms of “hypoplasia of the aortic outflow tract complex”.1 Sporadic cases with aortic atresia, an intact ventricular septum, and gross hypoplasia of the left ventricle, had been described long before, but it was Noonan and Nadas, in a landmark study, who coined the term “hypoplastic left heart syndrome”.2 The paediatric cardiac community has now accepted this term uniformly, although as we will see, problems remain with regard to precisely which malformations should be included within the “syndrome”. The term itself, nonetheless, is not beyond criticism. This is because, for those working in the genetic community, a “syndrome”, by definition, is a constellation of anomalies afflicting multiple systems of organs. The so-called “hypoplastic left heart syndrome”, however, almost always involves only the heart and the great arteries. Thus, according to the geneticists, it should not strictly be described as a “syndrome”, although the Nomenclature committee of the International Coding Project have marshalled arguments in favour of the term. In this review, nonetheless, we will skirt these problems with the use of “syndrome”, and simply describe the morphology as seen in patients unified because they have hypoplasia of the left heart.