Bilateral striopallidodentate calcinosis, also known as Fahr's disease, is characterized by symmetric calcifications of the basal ganglia, thalami, dentate nuclei of the cerebellum and white matter of the cerebral hemispheres. Intracranial calcifications are routinely observed with high sensitivity by Computed Tomography. Arachnoid cysts are benign congenital anomalies caused by accumulation of cerebrospinal fluid in cystic structures formed within two layers of arachnoid membranes. The aetiopathogenic and physiopathological mechanisms of arachnoid cysts are a source of controversy. In most of the cases radiologic imaging has in valuable. In this study we aimed to revise our knowledge of Fahr's disease which is seen rare and arachnoid cyst which is seen common.