An opportunity to study a neurologic case in which there were eosinophilic granulocytes in the spinal fluid brought to our attention the comparative rarity of this finding and the paucity of reports in the American literature. The first observations of eosinophilia in the cerebrospinal fluid were published independently in 1913 by Grund1and Water-house.2In both cases cerebral cysticercosis was the clinical diagnosis, and confirmation was established by postmortem studies. Among other cases described there were contributions by Schenk,3Buscaino,4Rizzo,5Ugurgieri,6Busse,7di Maggio,8Lange,9López Albo and Feijóo,10Canziani and Nobile11and Graña and Schenone.12The evaluation of this finding for the diagnosis of cerebrospinal cysticercosis has been discussed by Canziani and Nobile11and by López Albo and Feijóo10who agree that, whenever detected, it is practically pathognomonic. On the other hand, Lange9