Endoscopic surgery is popular in the neurosurgical field. The purpose of this study was to determine the role of endoscopy in obstructive hydrocephalus. From 1989 to 1999, we performed 81 endoscopic third ventriculostomies and 10 septostomies. Seventy-one of 81 operations were performed with endoscopic third ventriculostomy alone and 10 patients had endoscopic third ventriculostomy and ventriculoperitoneal shunt simultaneously. Age distribution varied from 2 months to 62 years of age. Our selection criteria included aqueductal stenosis (39 patients) and obstructive hydrocephalus due to tumor or cyst (42 patients). The most common candidate for endoscopic septostomy was atresia of the foramen of Monro (4 patients). Endoscopic septostomy was also performed to simplify shunting in patient; with multiseptated ventricle due to shunt infection, germinoma, thalamic tumor, craniopharyngioma, cyst and brain abscess. Sixty-five of 71 patients who were treated with endoscopic third ventriculostomy alone showed successful results (91.5%). However, 6 patients had unsatisfactory results and they needed a ventriculoperitoneal shunt. With no mortality, transient surgical complications were observed in 7 patients: 2 transient diabetes insipidus from electrical injury to the pituitary stalk, 1 epidural hematoma from sudden drainage of CSF, 1 delayed intraventricular hemorrhage. 2 obstruction of fenestration site and 1 transient memory disturbance from injury to the fornix. Endoscopic septostomy was useful in simplifying shunting in all cases with complicated hydrocephalus. Endoscopic surgery is straightforward and effective in appropriately selected cases with obstructive by drocephalus.