As a result of rapid developments in many fields of medicine in recent years, most pediatric emergency diagnoses can be made while the patient is still in the emergency department. Often, an accurate medical history and a physical examination are all the physician needs to make a diagnosis, but in some situations it is very difficult to identify children with dangerous conditions. Fever is one of these. We demonstrated that measuring levels of either C-reactive protein (CRP) or procalcitonin (PCT) was superior to a clinical evaluation in predicting serious bacterial infection in children aged 1 month to 3 years old. In another study, we showed that levels of proadrenomedullin, but not copeptin, may help to predict complications in children with community-acquired pneumonia and who therefore require a more aggressive therapy. As a omputerized tomography scan (CT scan) is potentially harmful, we found that measuring S100B protein was helpful in decreasing the number of imaging studies needed in the management of children suffering from a mild traumatic brain injury.