The authors report four hydrocephalic children with cerebrospinal fluid (CSF) edema extending along the ventricular catheter of an obstructed CSF shunt. Three of the patients exhibited massive CSF edema along the ventricular catheter, yet they manifested neither ventricular enlargement nor apparent periventricular CSF edema despite increased intraventricular pressure. These findings suggested ventricular tautness. The remaining patient, who had dilated ventricles with periventricular CSF edema, displayed CSF edema in a limited area along the ventricular catheter. Replacement of the obstructed peritoneal catheter of the shunt resulted in rapid improvement of the edema in all patients. In the three patients with massive CSF edema, however, a small lesion remained in the subcortical white matter along the ventricular catheter as demonstrated by computerized tomography and/or magnetic resonance imaging 3 to 5 years after shunt revision. It is concluded that shunt obstruction may result in massive CSF edema along the ventricular catheter in hydrocephalic children who have ventricular tautness after installation of the shunt causing irreversible although usually asymptomatic damage to the affected area of the brain.