The sella turcica usually appears partially empty in MR images obtained from patients with chronic elevation of intracranial pressure. The authors measured the size of the sella turcica to determine if enlargement of the pituitary fossa explains the partially empty sella associated with pseudotumor cerebri.The medical records from 2005 to 2011 of a single neuro-ophthalmologist were searched to identify consecutive patients with pseudotumor cerebri. Age-matched control patients were selected from the same practice. The sella turcica and pituitary gland were measured on sagittal T1-weighted MR images.Measurements were obtained for 48 patients with pseudotumor cerebri and 48 controls. The cross-sectional area of the sella was 38% greater in the patients with pseudotumor cerebri, with only a slight reduction in mean pituitary gland size.Chronic elevation of intracranial pressure is associated with bony enlargement of the sella turcica. Enlargement of the sella turcica contributes to its partially empty appearance.