All emergency departments should be prepared to care for a critically ill infant, including having the appropriate sized equipment. The most common diagnosis in admitted neonates include respiratory infections, sepsis, congenital heart disease, bowel obstruction, hypoglycemia and seizures. Febrile neonates are at high risk for sepsis and therefore need blood, urine and CSF testing. These patients should receive empiric antibiotic therapy in hospital. There are many life-threatening illness that can affect this population and is the responsibility of the emergency physician to assess the neonate, stabilize, narrow the differential diagnosis to the most likely and begin life-sustaining treatment. Very different types of illnesses can affect a child in the neonatal period and some can give us different clinical presentation. For example, the spectrum of congenital heart disease presenting in the newborn period and early infancy ranges from benign to catastrophic. Neonatal seizures may have subtle manifestations and require a different approach than seizures in older infants and children. This is a review of the more common but life threatening pathologic conditions in the neonate if not managed adequately.