Two cases of suprasellar subarachnoid cysts are reported. CASE I. The clinical symptoms of Case I consisted only of postural headaches. The midline suprasellar air-containing structure visualized on the pneumoencephalographic study was well delineated from the third ventricle and the patient did well after a limited operation (marsupialization). This type of suprasellar subarachnoid cyst might develop from the suprasellar subarachnoid cisterns. CASE II. Nanism, amenorrhea, retarded skeletal development together with lowered creatinemia and 17 hydroxy-corticosteroids were the main clinical signs in Case II. They were associated with a bilateral inferotemporal quadrantanopsia. Case II was compared with a nearly similar case already reported by Hardy and associates before the Canadian Neurological Society in June 1966. Both had a modified dorsum sellae with an inverted figure of 3 appearance of the clivus. Both had an important air-containing expanding lesion in the midline impossible to separate properly from the third ventricle. Both had an unfortunate outcome. This type of suprasellar subarachnoid cyst appears to develop from the floor of the third ventricle, sometimes in connection with an inflammatory process. Based on these cases, the radioclinical features were determined. A strong plea is made to radiologists to keep in mind the possibility of a complicated suprasellar subarachnoid cyst developing from the floor of the third ventricle with an inflammatory component. Sarcoidosis or tuberculosis should always be thought of in this area. When the roentgenologic changes would normally point to a craniopharyngioma, especially if the clivus has an inverted figure of 3 appearance, this diagnosis should be considered.