The temporal lobe agenesis syndrome is a rare congenital abnormality. This syndrome frequently has been described in association with arachnoid cysts or abnormal collections of cerebrospinal fluid. Arachnoid cysts develop most frequently in the middle cranial fossa and almost all these cysts are unilateral. Bilateral middle cranial fossa arachnoid cysts are extremely rare and only 9 cases have been reported in the literature. We present an adult case with bilateral arachnoid cysts and temporal lobe agenesis whose mental examination and neurologic assessment is normal. The cysts are demonstrated by CT and metrizamid CT cysternography.