Abstract Mediastinal teratomas are uncommon, fast-growing thoracic tumours, which are usually diagnosed in childhood or adolescence. Neonatal forms are the rarest and often present with life-threatening respiratory distress syndrome. In our case, respiratory failure in a neonate was aggravated by severe cardiogenic shock due to aortic and systemic venous compression, extreme heart displacement and rotation, necessitating an emergency operation on the first day of life.