With the advent of modern neonatology and the survival of most premature infants, necrotizing enterocolitis of the newborn (NEC) has become a relatively frequent illness. NEC, although affecting mainly premies, may still be found in any infant, even full term ones. We therefore believe that it is important for all physicians to become somewhat familiar with this entity. The pathogenesis of NEC is comprised of several variables: mesenteric ischemia, gastrointestinal immaturity, enteral feedings and even possibly infection. A diagnosis of NEC is based on a combination of clinical and radiological grounds. On radiographs, pneumatosis intestinalis and air in the portal vein are of special significance. NEC is classified in three broad categories: suspected NEC, definite NEC and advanced NEC. The treatment is either medical or surgical, depending on the severity and the evolution of the disease. It is important to emphasize that any infant who is deteriorating deserves very tight clinical and radiological follow-up. This follow-up should take place in a center where pediatric surgeons are ready to intervene rapidly should there be a need. Even if in some cases NEC is very severe, sometimes fatal, approximately 85% of infants suffering from it survive and among them more than 70% do so without any long term sequelae.