The term “empty sella” is a gross descriptive term introduced by Busch in 1951 (3) and applied to the appearance of the sella turcica when the diaphragma sellae is incomplete or forms only a small peripheral rim and the pituitary gland is not visible grossly as one views the sella turcica from above at necropsy or at surgery. Actually, the pituitary gland is not absent, but is flattened in such a manner as to form a thin layer of tissue at the bottom of the sella turcica. In 1924, Schaeffer (35) described the gross appearance of the diaphragma sellae in 125 cases and noted that it varied from a very dense and complete roof, transmitting the infundibulum, to a mere peripheral rim with a huge infundibular foramen. Busch (3) grossly examined 788 sellae of patients with no known pituitary disease and described three main types of the diaphragma sellae. In Type 1-A the diaphragma sellae forms a complete covering transmitting the hypophyseal stalk. Type 1-B exhibits a slight funnel-shaped depression in the completely formed diaphragma sellae. In Type 2-A the diaphragma sellae is incompletely closed with a 3 mm or less opening around the hypophyseal stalk. Type 2-B exhibits, in addition, a slight funnel-shaped indentation toward the middle. In Type 3 the diaphragma sellae is a peripheral ring of tissue 2 mm or less with (A) the pituitary gland freely exposed, but covered with an arachnoid membrane (Fig. 1, A); (B) an indentation of the pituitary gland, often eccentric; or (C) the pituitary gland flattened to the bottom. In these cases the sellae at first glance appear empty (Fig. 1, B). Type 3-C occurred in 40 cases, 34 females and 6 males, a 5.5 per cent incidence. Robertson (34) in 1957 demonstrated intrasellar air on pneumoencephalograms and Engels (10) in 1958 showed radio-graphically the presence of a hypophyseal subarachnoid space in a patient who had ethyl iodophenylundecylate (Pantopaque) in the pituitary fossa, secondary to an inadvertent intracranial spill during cervical myelography. That there are varying degrees of incompleteness of the diaphragma sellae and that there can exist an intrasellar subarachnoid space has been clearly shown by others (5–7, 12, 15, 21, 29, 30, 36, 37). It is the purpose of this paper to present the radiographic appearance of “empty sellae” and to suggest a mechanism of enlargement of the sella turcica other than by intrasellar neoplasm. Case Reports The following abstracted case reports of a group of females are presented to illustrate the roentgenographic findings characterized by globular sellae turcicae, ranging from normal size to what would be considered remodeled and enlarged. These changes will be related to the state of the diaphragma sellae and the cerebrospinal fluid (CSF) pressures. Case I: M. M., a 47-year-old female (height 5′4″ and weight 163 lb.), had a six-year history of spontaneous cerebrospinal fluid rhinorrhea.