Arachnoid cysts of the middle cranial fossa are probably not so infrequent as previously thought. Twenty-five cases are reported together with the most relevant clinical and radiological findings. The authors emphasize the importance of computerized tomography (CT) in providing pre- and postoperative anatomical and physiopathological information. The potential morbidity of these lesions is stressed and surgical indications are discussed with preference for a radical craniotomy rather than a shunt procedure.