We reiewed pathology specimens from 84 patients seen during a 10-year period with neonatal necrotizing enterocolitis, and these findings were correlated with clinical features. Coagulation (ischemic) necrosis, inflammation, and bacterial overgrowth were all present in the intestine of nearly all patients but with individual variability in the severity of these findings. Overall, coagulation necrosis was more severe than any other finding in most infants, indicating the importance of ischemia in the pathophysiology of necrotizing enterocolitis. Reparative tissue changes such as epithelial regeneration, granulation tissue formation, and fibrosis, found in two thirds of cases, suggested ongoing tissue injury of at least several days' duration. Birth weight, Apgar score, age, feeding status, and the presence of respiratory distress syndrome were not correlated with any particular histologic feature. The pathologic changes of necrotizing enterocolitis suggest that its cause is multifactorial, with ischemia, inflammation, bacterial overgrowth, and reparative tissue changes all playing important roles.