Naturally occurring neurologic disease in non-human primates may be attributable to a wide-range of causes, including infectious agents, congenital or acquired malformations, degenerative diseases, and, rarely, neoplasia. We report a case of ataxia and paresis in a juvenile rhesus macaque with ependymal-lined cerebral cysts. K E Y W O R D S ataxia, brain cyst, non-human primate, paresis | 379 PECORARO Et Al. How to cite this article: Pecoraro HL, Haertel AJ, Cullin C, Prongay K, Lewis AD, Ducore R. Cerebral cysts of ependymal or ventricular origin in a juvenile rhesus macaque (Macaca mulatta) with neurologic signs. J Med Primatol. 2019;48:378-380. https ://doi.