Introduction. Adrenocorticotropic hormone-secreting (ACTH-secreting) pituitary adenoma is the most frequently diagnosed pathology at the stage of microadenoma. Selective transnasal-transsphenoidal microadenomectomy is the most effective method of treatment. Materials and methods. We studied 35 cases of ACTH-secreting pituitary microadenomas in post-op period. All 35 patients underwent transnasal-transsphenoidal microsurgical removal of microadenomas, 8 patients underwent endoscopic assisted surgery. Results. In 75% of patients we found no visible changes of sella turcica, complex anatomy of veins and topography of tumor, pseudocapsule was marginally expressed, we found primary invasion of tumor into diaphragm of sella turcica and cavernous sinus. Conclusions. In 25% of studied ACTH-secreting pituitary microadenomas cases we found no complex microsurgical anatomy of tumor. Endocsope-assisted surgery facilitates approach to the pituitary fossa, facilitates radical removal of tumor, provides proper level of safety at surgery of pituitary gland.