The ability to noninvasively diagnose even the most complex congenital heart disease is one of the greatest advances in the care of children with cardiac defects. Initially, two-dimensional echocardiography displayed anatomy; later, Doppler allowed the quantitation of pressure and flow. Using these modalities, cardiac catheterization is unnecessary for most children with cardiac defects. Echocardiography also is routinely used for intraoperative and fetal cardiac imaging. Three-dimensional magnetic resonance imaging can now quantitate volumes of irregular shaped heart chambers (eg, the right ventricle) and blood flow (eg, as from a leaking valve). As technology moves further into the digital age, developments will continue to facilitate noninvasive diagnosis and treatment of children with congenital heart disease.