A flexible therapeutic ventriculoscope allowing for the use of a variety of different instruments has been developed. Endoneurosurgical instruments are composed of an endoscopic contact YAG laser endoprobe, grasping forceps and a punctured needle. Endoneurosurgical procedures include biopsies, III ventriculostomy, fenestration of the septum pellucidum, aspirations of cysts and excisions of tumors in the cerebrospinal fluid pathways. Our ventriculoscope allows the initial treatment for progressive hydrocephalus caused by intraventricular tumors to take the form of reducing ventricular size and decreasing intracranial pressure, and it can also be used to perform biopsy examinations, so that acceptable neurological outcomes and an accurate histological diagnosis can be obtained with fewer side effects. The subsequent therapies for hydrocephalus caused by intraventricular tumors include radical surgery for benign tumors, irradiation for radiosensitive tumors, and irradiation and/or chemotherapy for either malignant or disseminated tumors. We have tried to avoid the sequelae of shunt surgery and have achieved maximum effects with the minimum of procedures by using our ventriculoscope.