In ten adult patients various clinical signs and symptoms led to the diagnosis of an arachnoid cyst in the anterior and middle cranial fossa. In this study a functional relationship between these cysts and disturbances of higher cognitive processes is described. In addition, neuroendocrinological impairment were caused by arachnoid cysts reaching into the suprasellar cistern. Considering the short medical history of our patients we presumed the disturbances not to be primary, but rather secondary, caused by an expansion of the cysts' volume.