Hydrocephalus is usually treated by placing an extracranial CSF shunt. Endoscopic third ventriculostomy, however, has been revived recently as a less invasive method for treatment. We intended to avoid shunting or to eliminate the previously placed shunt with this procedure. The authors review their experiences on third ventriculostomy employing a flexible neuroendoscope under video monitoring in 14 cases of pediatric hydrocephalus. The result was that we succeeded in 11 cases (79%) by third ventriculostomy alone; we avoided shunting in 8 cases and eliminated a previously placed shunt in 3 cases. Clinical summary is shown on Table 1, and illustrative cases are presented with the figures and legend. The patients' group consisted of 8 males and 6 females. Their age ranged from 1 month to 17 years (average age, 6 yr) old. Background diseases of hydrocephalus were brain tumor in 6 cases, Chiari type I malformation in 3, intraventricular hemorrhage in 3, neonatal meningitis in 1 and arachnoid cyst in 1 case. In the remaining 3 cases, however, we failed to avoid the necessity of placing shunt because of indirect reasons (recurrence of tumor, infection after another operation, subdural fluid collection). There was no major complication in relation to third ventriculostomy, except for a moderate elevation of temperature of several days' duration following the procedure. Indication and outcome of this operation is also discussed. Endoscopic third ventriculostomy is an efficacious procedure for the treatment of hydrocephalus in selected patients.