Paediatric critical care units (PCCU) provide care to the most critically ill or injured children. Children are admitted to PCCU with a wide variety of illnesses, injuries and following a range of surgical procedures. High staff-to-patient ratios are required both because of the potentially rapid evolution of critical illness in children, as well as the complexity of the supportive therapies offered. Definitive evidence for specific paediatric therapies is often limited with extrapolation taken from adult experience, but there are increasing international collaborative efforts that have produced consensus treatment guidelines that serve to promote the use of best practice therapies. This article reviews therapies and techniques that define care in the PCCU and in particular outline principles of management of acute respiratory distress syndrome (ARDS), septic shock and traumatic brain injury (TBI). Neonatal and cardiac intensive care medicine topics are outside the scope of this article.