We describe the clinical, radiological and neuropathological findings in an adult AIDS patient presenting with ventriculitis and hydrocephalus as the primary manifestations of cerebral toxoplasmosis. Clinical symptoms including fever, headache, changes in mental status and focal neurological deficits were non-specific. Cranial computed tomography showed a subtile ventricular dilatation whereas magnetic resonance imaging disclosed triventricular hydrocephalus due to stenosis of the aqueduct and a periventricular nodular rim of high signal intensity on T2- and proton density-weighted images. This rim also showed a slight enhancement on post-contrast T1-weighted images. Focal intracerebral lesions could not be delineated, neither by neuroimaging nor by pathology. Neuropathological examination showed severe ventriculitis with large ependymal and subependymal necrosis as well as dilatation of the lateral and the third ventricle. The only microorganism demonstrated at histology in the central nervous system was Toxoplasma gondii. We conclude that ventriculitis and hydrocephalus without any focal parenchymal lesion may be the only manifestations of CNS toxoplasmosis. It is important to recognize this unusual form of presentation of cerebral toxoplasmosis in order to perform specific therapy.