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