We present an infant, two days of age, with a cyanotic attack, which needed additional examination. A conventional chest X-ray showed an intrathoracic mass, but could not differentiate between the differential diagnostic options. An additional CT scan of the thorax could not give conclusive information. Ultrasound examination of the chest and upper abdomen showed a evidential hernia diaphragmatic with herniaton of the liver. With this case in mind we outline the different forms of radiological diagnostics. We emphasize the role of a relatively plain diagnostic technique as ultrasound over more invasive techniques such as MRI or CT, for differentiation of intrathoracic masses, showed on a conventional chest X-ray.