Two caged Chinchillas that died with convulsions had a focal necrotic meningoencephalitis of toxoplasmic origin. Independently of and remote from this inflammatory reaction were several lobulated Frenkelia cysts up to 0.6 mm diameter in the brain. Morphologically and in the way they stained they resembled Frenkelia in various Microtus-species and in Ondatra zibethica. Although toxoplasmosis commonly is found in the Chinchilla this is the first report of Frenkelia in this species. Ecological considerations suggest that the Chinchilla might be susceptible to a Frankelia usually occurring in free living other species.