The diagnosis of necrotizing enterocolitis (NEC) in neonates may be made by clinical presentation, roentgenographic findings, or a combination of both. Diagnosis leads to immediate treatment including nasogastric suction, parenteral antibiotics, plasma, and close monitoring of clinical, roentgenographic, and laboratory findings. Occasionally, neither the clinical nor plain roentgenographic appearance of an infant allows the diagnosis of NEC to be made or excluded with confidence. In such infants portable isotonic metrizamide gastrointestinal (GI) series were used to help make the decision of whether to begin treatment for NEC or to continue feeding the patient. Of 15 patients examined, two exhibited signs of NEC and were successfully treated medically without GI (tract) sequelae. Twelve neonates had normal results of metrizamide GI series and ten were immediately fed with no GI complication. One of these 12 infants had feedings withheld for several days as a result of a positive blood culture. One infant with severe cardiac and pulmonary disease had profound adynamic ileus and could not be fed. We have found the metrizamide GI series to be a useful study in neonates suspected of having NEC.