Necrotizing enterocolitis (NEC) is not a new disease but one that has been reported since special care units began to house preterm infants. It was observed in foundling hospitals in Paris [Billard, 1828] and Vienna [Bednar, 1850] and, as it occurred in clusters, was regarded as a nosocomial infection in the infant hospitals of Zurich [Willi, 1944] and Berlin [Ylppö, 1931]. Clinical and patho-anatomic characterization was achieved by Schmidt and Quaiser in 1952. The unproven hypothesis of mesenteric hypoperfusion as a major etiological factor arose from animal models and analogous perforating disorders in term infants. Despite similarities between NEC and clostridial infections, few studies employed anaerobic culture techniques. The pathogenesis remains unclear and its distinction from related disorders uncertain. It is unlikely that strategies to prevent NEC will be successful unless the disease is better understood.