Macroscopic and histological study of a case of unilateral hydrocephalus in a young wild European brown hare (Lepus europaeus) is reported here. Morphological changes were mostly massive dilatation of the left lateral ventricle, atrophy of the cortex and a striking reduction of the corresponding white matter. Lymphocytic cell infiltrates and hemosiderin-laden macrophages in the choroid plexus and meninges also were observed. Although the exact cause of the lesions was not found all findings suggested a hydrocephalus of possible traumatic, infectious or congenital hypoplasia origin.