A fatal case is reported concerning a severely immunocompromised 50-year-old female renal transplant recipient who developed fever and confusion. Cerebral imaging with contrast-enhanced computed tomography (CT) scans showed no abnormalities while subsequently performed magnetic resonance imaging (MRI ) showed clear abnormalities in the basal ganglia. By that time serology and polymerase chain reaction had confirmed the diagnosis of cerebral toxoplasmosis. Because of the suboptimal sensitivity of these tests negative results should be handled with care. Once cerebral toxoplasmosis is suspected in at-risk patients, treatment should be started empirically pending the confirmation of the diagnosis. A normal cerebral CT scan does not preclude cerebral toxoplasmosis.In these situations MRI can give important additional information.