Fahr's disease (FD) is characterized by sporadic or familiar idiopathic calcification of the basal ganglia, dentate nuclei of the cerebellum, and centrum semiovale, mainly presenting with movement disorder, dementia, and behavioral abnormalities. We described a rare case of Fahr's disease presenting at onset only with behavioral and neuropsychological alterations, whose diagnosis was supposed only after a brain CT, which showed extensive bilateral calcifications in the dentate nuclei of the cerebellum and basal ganglia. Since the onset of Fahr's disease may be a dysexecutive syndrome with behavioral abnormalities, the clinical and radiological features are really important to do the appropriate diagnosis.