A chest x-ray (or radiograph) makes a picture of the heart, lungs, and blood vessels in the chest. The bones are also visible in the "picture" that is taken.

X-rays are produced by directing electromagnetic radiation of very short wavelength into an object. Unlike the longer wavelengths of visible light radiation, x-rays can penetrate many opaque objects. Because large quantities of radiation may be harmful, great care is taken to limit the intensity and length of exposure and to avoid unnecessary radiography.

Though it does not reveal details of the internal heart structure as well as cross-sectional echocardiography, chest radiography remains an important tool for recognizing and assessing congenital heart disease. It is valuable as a screening method because of its speed and availability. Chest x-rays are also convenient for assessing the size, position, and morphology of the heart and great arteries, and for determining pulmonary features. In addition, chest x-rays allow the recognition of other conditions affecting the patient, such as skeletal abnormalities and pneumonia.