The hypoplastic left heart syndrome encompasses a spectrum of cardiac malformations that are characterized by significant underdevelopment of the components of the left heart and the aorta, including the left ventricular cavity and mass. At the severe end of the spectrum is found the combination of aortic and mitral atresia, when the left ventricle can be close to non-existent. At the mild end are the patients with hypoplasia of the aortic and mitral valves, but without intrinsic valvar stenosis or atresia, and milder degrees of left ventricular hypoplasia. Although the majority of the patients are suitable only for functionally univentricular repair, a small minority may be candidates for biventricular repair. The nature of the syndrome was a topic for discussion at the second meeting of the International Working Group for Mapping and Coding of Nomenclatures for Paediatric and Congenital Heart Disease, the Nomenclature Working Group, held in Montreal, Canada, over the period January 17 through 19, 2003. Subsequent to these discussions, the Nomenclature Working Group was able to create a bidirectional crossmap between the nomenclature initially produced jointly on behalf of the European Association for Cardio-Thoracic Surgery and the Society of Thoracic Surgeons, and the alternative nomenclature developed on behalf of the Association for European Paediatric Cardiology. This process is a part of the overall efforts of the Nomenclature Working Group to create a comprehensive and all-inclusive international system of nomenclature for paediatric and congenital cardiac disease, the International Paediatric and Congenital Cardiac Code. In this review, we discuss the evolution of nomenclature and surgical treatment for the spectrum of lesions making up the hypoplastic left heart syndrome and its related malformations. We also present the crossmap of the associated terms for diagnoses and procedures, as recently completed by the Nomenclature Working Group.