In the past 10 years, the diagnosis of pseudoobstruction lasting more than two months was confirmed in 10 infants after sepsis, meconium ileus, and Hirschsprung's disease were excluded, and surgery or autopsy failed to demonstrate a site of mechanical intestinal obstruction. Four infants had undergone prior operation for another anomaly: gastroschisis (2) and ileal atresia (2). Five of the remaining infants also had megacystis. The lack of coordinated intestinal motility was best appreciated by radiocontrast small bowel studies, which showed degrees of aperistalsis or segmentation. Rectal manometric studies were not helpful. Histology of the intestine was normal in seven, while a gross deficiency of nerve fibres was noted in one patient and a myopathy of smooth muscle in another. A variety of drugs used to stimulate peristalsis were ineffective. Seven patients had 25 operations, often to exclude mechanical causes of obstruction. The mainstay of treatment was TPN and intestinal decompression. Six children survived; their ages ranged between 8 months and 9 years (median age, 16 months). There has been improvement in intestinal peristalsis in five children, three of whom now tolerate a regular diet and two of whom are on TPN and are currently increasing oral intake. Four infants died, two from sepsis, two from TPN-related hepatic failure. In contrast to previous reports, we conclude that intestinal pseudoobstruction may be self-limited in some neonates, including those with megacystis. Therapy should consist of long-term nutritional support and treatment of other anomalies that may be present.