The infant or child that presents with abdominal pain must be evaluated with a careful history, physical examination, and selective laboratory studies. There are a few diagnoses that the emergency physician should always consider as "life threatening." In the event of any uncertainty in the diagnosis of conditions like appendicitis, pyloric stenosis, or intussusception, the child or infant should be observed carefully over time with appropriate laboratory/radiologic studies ordered to further delineate pathology. Ultrasound evaluation of children with abdominal pain continues to be one of the most valuable tools to help diagnose different conditions.