Necrotizing enterocolitis is the most common acquired gastrointestinal emergency of premature infants. It occurs less frequently in older children who are under great stress (e.g., congenital heart disease). Necrotizing entercolitis is related to infection and ischemia, commonly affecting the ileum and acending colon. It usually presents during the first or second week of life with bloody stools (50%), explosive diarrhea, bilious emesis, mild respiratory distress, generalized sepsis, distention of the abdomen, and feeding difficulties. It requires an immature gut and time for gut to become colonized in order to develop. These patients typically have been fed. The treatment is bowel rest and antibiotics and surgery for bowel perforation.