The present study has the purpose of showing the possible value of the EEG in the diagnosis of brain cysticercosis. The diagnosis of cysticercosis was based on (1) radiological calcification, (2) characteristic spinal fluid findings (increase of cells, increase of eosinophils and positive test for cysticercosis) and/or (3) neurosurgical findings. The total number of cases was 118 (14 verified by surgical approach, 35 diagnosed by X ray examination and 42 by the spinal fluid examination) : in 16 cases there were association of surgical and spinal fluid positive findings; in 4 cases there were surgical findings and X ray positive findings; in 7 cases there were spinal fluid and radiological positive findings. The surgical cases were mostly of cysticercus of the posterior fossa because of the spinal fluid blocking that asks such therapy. The patients were divided according to the localization of the cysticercus (1) on the cortical surface, (2) at the base of the brain and the posterior fossa, and (3) diffuse cysticercosis. The localization of the cysticercus was possible by the evaluation of the clinical signs, the radiological calcification or the neurosurgical finding of the cysticercus. The EEG records were analysed according to the changes possibly due to the lesion caused by the cysticercus (chronic and diffuse meningo-encephalitis of the brain surface, arachnoiditis of the base and of the posterior fossa, inflammatory reaction inside the fourth ventricle, with subsequent spinal fluid blocking and intracranial hypertension). The analysis showed: 1 - Focal paroxysmal changes have indicated the great incidence of epileptic seizures in these patients; 2 - δ waves were more frequent when the lesion was located in the posterior fossa. The meningo-encephalitis on the cerebral surface did not show EEG signs of acute brain involvement; 3 - θ waves were seen very seldom and were present only on those patients with signs of basal or posterior fossa involvement (due to intracranial hypertension probably) due to involvement of mesencephalic structure; 4 - The normal EEG was very rare in patients with cerebral cysticercosis and did not give any information regarding the localization of the cysticercus; 5 - Changes on background activity (disorganization or discrete slow waves) have been noticed in all groups of patients; 6 - In patients with diffuse cerebral cysticercosis the EEG changes (disorganization on background activity, slow waves or signs of focal activity) did not show striking difference from those patients with localized cerebral cysticercosis; 7 - The calcified cysticercus on the cerebral surface (chronic cysticercosis) was coincident more often with focal activity on the EEG, than on the group of not calcified cysticercus (recent, cysticercosis); 8 - The incidence of pathological EEG was the same on both groups (calcified and non calcified cysticercosis). The EEG on the last group showed very often δ waves.