Background. Gamma knife radiosurgery of pituitary adenomas is considered to be very perspective. It can be a very useful complement of traditional microsurgery, pharmacotherapy or fractionated radiotherapy which are seldom a sufficient treatment on their own. The modern radiosurgery does not offer the experience representative enough in this indication. We can offer results of medium long follow-up for tumor growth and hormonal hypersecretion of pituitary adenomas in a relatively large series of patients. Methods and Results. We have analyzed a group of 163 patients with pituitary adenoma treated with gamma knife during 5 years and followed 12-60 months, median 24 months after irradiation. An antiproliferative effect has been achieved in 1-2 years using the minimal dose to the margin 16-35 Gy, median 20 Gy in all our patients who were controlled by MRI (n=126 patients). One half of these adenomas evidently decreased their size. Our effective antiproliferative dose was safe for the surrounding structures. The hormonal normalization has been achieved at 50.4 % from 133 hypersecreting adenomas (39/91 = 43 % of acromegalics, 11/13 = 85 % of patients with Cushing’s disease, 2/9 = 22 % of patients with Nelson’s syndrome, 11/18 = 61 % of prolactinomas). The median latency was 12 months. The minimal dose to the margin was 10-45 Gy, median 35 Gy. Rare side effects were provoked only by increasing the dose to influence the hypersecretion - the development of partial hypopituitarism in 3.1 % of patients, the panhypopituitarism in 0.6 % of patient and there was 1 hemianopic visual field defect (0.6 %). Conclusions. Radiosurgery by gamma knife has a similar value for pituitary adenomas as microsurgery has with different distribution of advantages and drawbacks. This makes it suitable for the combined treatment where pharmacotherapy has its place under special conditions. Fractionated radiotherapy has now a marginal importance.

        Key words: pituitary adenomas, Gamma Knife, antiproliferative effect, normalization