Suprasellar arachnoid cysts are expansive intracranial lesions with a very low incidence. Due to the availability of computed tomography (CT) and magnetic resonance (MR) they are nowadays diagnosed more frequently. The authors present their experience with two arachnoid cysts in the suprasellar region followed up for more than 10 years. They emphasize the importance of CT ventriculography in the differential diagnosis of a cystic lesion as compared with a dilated third ventricle with regard to preoperative decision taking and postoperative follow-up. An arachnoid cyst is obviously a develop- mental or acquired disorder of the arachnoid membrane and the theory of „active secretion“ seems the most feasible explanation of its growth. In both instances successful microsurgical extirpation by the subfrontal route was made and decompensation of the hydrocephalus was achieved, a subsequent shunt being essential for stabilization of the patients. The decisive factor for the therapeutic tactics is therefore the presence of hydrocephalus and its subsequent behaviour. The recent introduction of endoscopic methods extended therapeutic possibilities. Despite this direct decompression of the optic nerves and extirpation of the cyst remain one of the therapeutic methods. The development of hydrocephalus and its careful postoperative follow-up seems decisive for the further fate of patients, regardless of the surgical technique.

        Key words: arachnoid cyst, hydrocephalus