Sestre milosrdnice University Hospital has celebrated its 155th anniversary. In this period, it has been the origin of Croatian medical masterminds and a place of numerous pioneer events. After V. Horsley, in 1904, completed the first pituitary adenoma surgery by transcranial approach, and Schloffer, in 1906 by transsphenoidal approach, numerous surgeons have accepted these procedures depending on their affinity and equipment. A. Blasković did the first six transsphenoidal surgeries on the pituitary tumors in 1922. A. Sercer published a paper in 1926 "When and how to operate pituitary tumors" in which he described his experience in surgically treating six pituitary tumors by transnasal approach. By arrival of a neurosurgeon, D. Riessner, transcranial approach became a dominant method in treating extrasellar pituitary tumors. At the same time, smaller intrasellar adenomas were operated at the ORL clinic by transnasal approach. In 1963 I. Padovan published a paper describing his experience in implanting radioactive gold (Au198) in pituitary tumors. Following the D. Riessner's retirement, N. Popov continued to use transcranial approach in treating pituitary tumors with admirable results. In 1970, I. Padovan published a work in which he described 26 pituitary tumors treated by transsphenoethmoidal approach. Since 1982 until today Z. Gnjidić has performed surgery on more than 1000 patients using transsphenoidal approach. The above mentioned results belong to the top ten world series.