We reviewed surgical or autopsy specimens of the gastrointestinal tract from 14 patients with necrotizing enterocolitis(NEC) to define the specific pathologic findings and the pathologic changes of the bowel in the premature and fullterm infants, and then to see how these findings are related each other and to clinical features. In two-thirds of patients two or more continuous segments of the gastrointestinal tract were affected, and the ileum and colon were by far the most common sites of involvement. Pathologically, coagulation necrosis, inflammatory reaction, ulceration, microthrombi, overgrowth of microorganism, and perforation were the leading changes of NEC. On the basis of these histopathologic findings of the involving intestine, we could classify the pathology of NEC into two different histologic types. Type 1 and II are thought to represent pathologic changes of the intestine in acute and chronic stages of disease process. The symptom duration of the patients was significantly different between two types. The pathologic changes of the involved bowel were similar in both premature and fullterm infants, although the premature tended to have type 1 and the fullterm babies had more cases of type II. These pathologic changes could be associated with various clinical manifestation of NEC.