Idiopathic giant-cell granulomatous hypophysitis is a chronic inflammatory disorder of the pituitary gland. It presents clinically as a sellar mass lesion with pituitary insufficiency and/or hyperprolactinemia, and is radiologically indistinguishable from a pituitary tumor. In most of the previously reported cases the documentation of the disorder has been limited to autopsy tissue. Only a few cases documented by biopsy have been recorded. Four cases are presented here with radiological, endocrinological, and surgical findings. The appropriately documented cases collected from the literature and the present series are reviewed and the incidence, patterns of clinical and radiological presentation, and operative management of this disorder are discussed. This entity should be considered when evaluating patients with a pituitary mass and evidence of hypopituitarism and hyperprolactinemia.