Non-traumatic thoracic emergencies in children are very frequent, and they usually present with breathing difficulties. Associated symptoms may be feeding or swallowing problems or less specific general symptoms such as fever, sepsis or chest pain. The emergencies always require a rapid diagnosis to establish a medical or surgical intervention plan, and radiological imaging often plays a key role. Correct interpretation of the radiological findings is of great importance in diagnosing and monitoring the illness and in avoiding serious complications. Plain radiography with fluoroscopy still remains the most important and frequently used tool to gain information on acute pulmonary problems. Ultrasound is the first choice for the detection and treatment of simple and complicated pleural effusions. Cross-sectional techniques such as multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) are mainly used to study pulmonary/mediastinal masses and congenital abnormalities of the great vessels and the lungs. This article will discuss the choice of imaging technique, the urgency of radiological management and the imaging characteristics of acquired and congenital causes of non-traumatic thoracic emergencies. They represent common conditions involving the respiratory tract, chest wall and the oesophagus, as well as the less frequent causes such as tumours and manifestations of congenital malformations.