The case histories of seven children with prehepatic portal hypertension are presented. An umbilical vein catheter was introduced in six of the seven patients during the neonatal period for administration of fluids, including hypertonic and alkaline solutions. There appears to be a relationship between umbilical vein catheterization and thrombosis of the portal system. The methods of treating this condition are controversial. The most important sign is bleeding from oesophageal varices. Elective portosystemic shunts give the best operative results. A conservative policy, however, does not appear to have a higher mortality and probably results in a lower morbidity. Our present management is therefore conservative.