Eosinophil cells play an important role in the signalization of cerebrospinal fluid (CSF) by inflammatory diseases of central nervous system and its leptomeningeal coverings (CNS), according to present data on neuroimmunology. The extent of their participation in local immunological phenomena is evaluated, and data on other changes in the CSF cytoprotein dual were considered for comparative purposes. CSF of two types of inflammatory diseases of the CNS were studied for this purpose: samples of 35 patients in early stages of acute eosinophilic leptomeningites possibly of viral origin (first group) and 20 samples of 10 patients with neurocysticercosis (second group). Samples of the second group were collected in the early stages of each one of two episodes of exhacerbation in the inflammatory reaction observed at each one of the two series of administration of Praziquantel, a pirazino-isochinoleinic derivate which action upon cysticerci has been reported. Statistical analysis shows that participation of eosinophil cells in the inflammatory response does not differ in the two groups. Their participation is related to changes observed in the CSF cytoprotein dual rather than to the type of the inflammatory model: acute and monophasic in the first group, and chronic and repetitive in the second. Gamma globulins participe in the exhacerbation of CSF inflammatory reaction in neurocysticercosis but their behaviour not always is similar. In some instances it is similar to that found in other chronic and repetitive inflammatory models, as multiple sclerosis for instance.