A plasma cortisol less than 50 nmol/L in the early postoperative stage after transsphenoidal surgery for Cushing disease has been proposed as predictive of cure. Data on postoperative plasma adrenocorticotropin (ACTH) are scarce. The objective of this study was to establish whether plasma ACTH, in the early postoperative period after transsphenoidal surgery for Cushing disease, can predict cure and how its prognostic value compares with that of plasma cortisol. We analyzed 13 patients with Cushing disease (mean age, 43 years) treated by transsphenoidal surgery. Serum cortisol and plasma ACTH samples were taken on the seventh day after surgery. Follow up was between 12 and 55 months (mean, 34 months). During this time, samples for basal serum cortisol and after stimulation with 250 μg ACTH1–24, basal plasma ACTH, 24-hour urinary-free cortisol, and plasma cortisol after an overnight dexamethasone suppression test were measured periodically to evaluate their clinical status. Twelve of the 13 patients were in remission during the follow-up period. The early postoperative serum cortisol level was 50 nmol/L or less in only 4 of the 12 patients in remission, whereas the plasma ACTH level was 2 pmol/L or less in 6 of these patients. Normal values for plasma ACTH were between 2 and 12 pmol/L. The value of plasma ACTH level measured in the first postoperative week is not a better predictor of cure than early postoperative serum cortisol level.