Ultrasound has been used in cardiac diagnosis since the 1960s. The original modality used was M-mode, which recorded the movement of heart structures relative to a single line of sound passed through the heart and was displayed as a paper tracing. During the 1970s, a two-dimensional image became possible, but it was a static image, which had limited value for cardiac evaluation. However, by the end of the 1970s, advances in ultrasound equipment allowed the heart to be displayed in real-time. This technology was applied initially in the adult and subsequently in the child. Echocardiography proved particularly suitable for children, partly because it is non-invasive and repeatable, but also because most heart disease in children is due to malformation of anatomical structure, which ultrasound can ideally display. At the same time, obstetric ultrasound was progressing rapidly and descriptions of the appearances of malformations in most fetal systems began to be published by the end of the 1970s. It was not until real-time equipment became generally available in obstetrics that the fetal heart could be satisfactorily evaluated. This led to descriptions by several authors of normal fetal cardiac anatomy as seen echocardiographically in 1980. The appearances of the echocardiogram in different forms of congenital heart disease (CHD) in children were published in the late 1970's, setting the stage for diagnosis in fetal life. As a result, by the mid-1980's, most major forms of CHD had been detected prenatally.