Progressive ataxia, delayed growth, dementia and tremors were noted in a female African lion (Panthera leo) cub at the Tel-Aviv Ramat-Gan Zoological Center (Israel). The lioness was 3-mo-old when clinical signs were first noticed. Repeated neurological evaluations and blood tests were conducted in an attempt to establish a diagnosis. A congenital abnormality was suspected and the lioness died 6 mo later. Post mortem examination revealed an Arnold-Chiari malformation. The abnormality was classified as a Chiari type 2 malformation, based on the herniation of the cerebellar vermis and paravermis and the slight caudal displacement of the medulla, combined with lack of displacement in other parts of the brainstem.