Under the supposition that ACTH secretion will be compromised by surgical trauma, patients with pituitary adenomas undergoing transsphenoidal adenomectomy are frequently given corticoids, even though this therapy is controversial. We studied 10 patients with pituitary adenomas whose adrenocortical function was sufficient prior to surgery. The ACTH and cortisol levels rose significantly during surgery in all of these patients. Five patients completed a two-year postoperative follow-up period and their ACTH and cortisol values remained within normal limits. It may be that patients undergoing transsphenoidal surgery for pituitary adenomas do not need perioperative glucocorticoid treatment, since the hypophyseal-adrenal axis does retain its integrity.