The Authors describe the clinical and anatomo-histopathological findings observed in a case of hydranencephaly occurred in a 7-months-old, Holstein-Friesan calf. Clinically, a poor body condition, associated with skeletal muscle atrophy, regurgitation and neurological deficits compatible with a diffuse cerebrocortical involvement, were observed. At necroscopy, an abnormal dilation of lateral ventricles, along with cerebrospinal fluid accumulation and marked atrophy of the brain parenchyma, were found. Histologically, degenerative and necrotic changes involving the brain tissue, associated with prominent lymphoid cell depletion at the level of several limphoyd districts, were observed. On the basis of the above finfings, a number of plausible aetio-pathogenetic hypotheses are made and discussed.[...]