Anaemia is a common issue in the paediatric age group, and it is not uncommon to encounter severe cases of anaemia in the Paediatric Emergency Department. The correct identification of patients requiring urgent care is of central importance in order to provide timely interventions. However, considering that most patients are hemodynamically stable, transfusions are not always mandatory. Even in the setting of the Emergency Department, it is possible to narrow the differential diagnosis with specific laboratory tests. We present three exemplary cases from the experience of a Paediatric Emergency Department that will help us provide a summary of the diagnostic and therapeutic approach to severe anaemia in infants and children.