Considerable advances in ultrasound technology and close collaboration between the specialties of paediatric cardiology and fetal medicine have resulted in the increasing ability to diagnose congenital heart disease before birth over the last two decades. Fetal cardiology differs from paediatric cardiology not only in the spectrum of diseases seen, but also in the assessment of function because of the extended feto-placental circulation. Importantly, outcomes for specific lesions may differ as extracardiac abnormalities and chromosomal defects may alter the prognosis of otherwise straightforward cardiac lesions such as tetralogy of Fallot.1 Historically the examination of the fetal heart and circulation developed separately, obstetricians using Doppler to examine the uteroplacental circulation to study the pathophysiology of pregnancy,2 3 while cardiologists focused their attention on the morphological aspects of cardiac development using M mode and Doppler.4 5 In today's practice a comprehensive evaluation of the fetal cardiovascular system includes both structural and functional assessment using new technologies to monitor the progression of cardiac defects and to aid management decisions such as the need for early delivery, treatment of arrhythmia or for interventions such as balloon valvuloplasty of semilunar valve obstruction.