Our aim was to analyze the correlation of early postoperative cortisol levels in patients after transsphenoidal pituitary adenoma surgery compared to the standard dose ACTH test and Insulin tolerance test (ITT) several months later. We retrospectively reviewed data from 94 patients operated for pituitary adenoma in years 2009-2012. The comparison of day 7 (median) postoperative basal cortisol levels and 3.6 months (median) after pituitary adenoma surgery stimulation test - standard dose 250 μg 1-24ACTH test in 83 patients or ITT in 11 patients were performed. All 16 patients with early postoperative cortisol levels >500 nmol/l proved a sufficient response in the stimulation tests. At basal cortisol levels of 370-500 nmol/l the sufficient response was found in 96 % (27/28) of patients. In the postoperative basal cortisol levels 200-370 nmol/l we found a preserved corticotroph axis later on in 88 % (28/32) of cases. Patients with basal cortisol levels 100-200 nmol/l had a maintained corticotroph axis function in 8/11 cases - 73 %. All patients with an early postoperative basal cortisol level above 500 nmol/l proved in the stimulation tests a preserved corticotroph axis function. The interval 370-500 nmol/l showed a minimal risk of postoperative adrenal insufficiency., V. Hána Jr., J. Ježková, M. Kosák, M. Kršek, J. Marek, D. Netuka, M. Hil, V. Hána., and Obsahuje bibliografii