Ascites fluid was obtained intraoperatively in 12 consecutively treated neonates (6M, 6F, mean weight 940 g, mean gestational age 27th week, lethality 3/12) suffering from necrotizing enterocolitis (NEC). The concentrations of endotoxin and cytokines (IL-1, IL-6, TNF) were determined. Endotoxin and interleukins were excessively elevated in all patients, TNF only in those who survived. Postoperative treatment included the use of a continuous abdominal lavage system. This therapeutical procedure allows the elimination of endotoxin and cytokines out of the abdominal cavity in order to reduce their adverse biological effect.