One hundred newborns with neonatal necrotizing enterocolitis (NEC) were treated surgically according to a uniform protocol between July, 1980 and June, 1988. The infants (53 females, 47 males) weighed between 600 and 3,800 g, averaging 1,500 g. Twenty-eight weighed less than or equal to 1,000 g, 38 weighed from 1,001 g to 1,500 g, and 34 weighed more than 1,500 g. Median age at the time of surgery was 14 days. Surgery was performed for pneumoperitoneum in 40, a "positive" paracentesis in 51, and for other reasons in 9 infants. A paracentesis was performed if intestinal gangrene was suspected clinically. Resection of gangrenous bowel with exteriorization was the usual procedure; in only 5 patients was primary closure performed. The hospital survival for the infants was 54% for the group weighing less than or equal to 1,000 g, 74% for the group weighing from 1,001 g to 1,500 g, and 79% for the group weighing more than 1,500 g. Overall hospital survival was 70%; it was 81% for those having a definitive procedure (excluding 14 infants with NEC "totalis"). There were 3 late deaths from causes unrelated to NEC. Significant long-term complications included failure-to-thrive in 23% and stricture formation in 30% of the survivors. Long-term follow-up showed gastrointestinal status to be normal in 74%; only 8% have persistent major gastrointestinal dysfunction. Mental and motor development was considered grossly normal in only 53% of the patients.