Observing pediatric patients in an OU (whether a pediatric or combined or hybrid unit) has many advantages: better patient care, a decrease in missed diagnoses and acuity, better risk management, decreased malpractice liability, cost effectiveness, increased patient and family satisfaction, and psychosocial benefits. Key principles of observation medicine (purpose, time frame, general patient inclusion and exclusion criteria, administration, CQI, and so forth) are equivalent for pediatric and adult observation patients, but there are important differences. Unique characteristics of pediatric observation patients include specific diagnosis, decreased length of stay, less need for cardiac monitoring, a highly variable admission rate, and a decreased percentage or admission rate to the OU from the ED. Whereas the adult OU is primarily a cardiac-monitoring unit, the pediatric OU is a respiratory and infectious disease unit with a frequent need for an i.v. therapy and hydration. Types of pediatric patients commonly treated in an OU include respiratory illnesses (asthma, croup, bronchiolitis, pneumonia), gastrointestinal disorders (gastroenteritis, abdominal pain), dehydration, infections (fever, cellulitis, lymphangitis, pyelonephritis or UTI), overdoses or poisonings, and seizures.