The radiologic criteria for a preopera-tive diagnosis of intracranial cysticercosis follow this pattern in air studies: Internal hydrocephalus without detectable tumor; Dilatation of the ventricles, usually without ventricular displacement; Displacement or deformity of the ventricles (about 2 to 2.5% of cases); Variations in dimensions of lateral ventricles which may be asymmetrical. This sign is the most important of the group; Direct visualization of the parasite (over 85% of the cases) by: Recognition of calcifications of the shape and size of dead larvae where the calcified scolex and some part of the cystic wall should be identified (better seen on plain skull roentgenograms). Evidence of soft-tissue masses shaped like vesicles of Cysticerci, usually inside the ventricles or cisternae. These range in size from a few millimeters to 2 or 3 cm and eventually deform the ventricular walls. Quite rarely, the finding of larvae with evaginated scolices, attached by hooks and suckers to the ventricular wall of a lateral ventricle. If 1 parasite is within the skull, especially if in the brain convexity, more cysts will usually be found in the basal cisternae. The evidence of typical calcification does not rule out living intraventricular, subarachnoidal, or pia arachnoidal Cysticerci; if the parasite is found in any part of the body, as a rule it may be expected to be encountered in the skull, mainly in the basal cisternae.