Positive contrast ventriculography using methylgucamine iothalamate 60%(Conray ) for 23 studies of 23 patientswas reported. This procedure is useful in the diagnosis of the midline cerebral tumors including third and fourthventricular, posterior fossa lesions and occlusive hydrocephalus. The third ventricle and cerebral aqueduct werewell visualized accurately and clearly on this study. The fourth ventricle was visualized clearly but less thanthe third ventricle and cerebral aqueduct. This study revealed lesions as follows ; Pinealoma 5 Hydrocephalus 4Third ventricular lesions 2 Fourth ventricular lesions 2 Posterior fossa lesions 2 Others 8 Nausea, Vomiting andheadache were most common reaction after procedure. The most severe reaction was convulsions followed by death.The procedure is simple and safe if a few precautions are given.