Abstract： Objective To evaluate long-term efficacy of gamma knife on the treatment of pituitary microadenoma.Method We followed up all the patients of pituitary microadenoma performed with Leksell gamma knife in our unit during 1995.8-1998.12,in whom 109 cases were obtained which information fitting our demand.Results In the imaging follow-up,the number of vanishing,diminution,unchanging and augmentation of tumor volume was in 45、37、22 and 5 cases respectively.In the endocrine follow-up,the number of complete recovery of hormone was in 39 cases,partly recovery in 23 cases,no marked change in 15 cases,and keeping on rising in 14 cases.In our group,33 cases suffered from hypopituitarism before gamma knife,among which 28 cases recovered normally after radiosurgery,achieving effective percentage of 84.8%.There were 8 cases showing some hypophyseal hormone lower than normal level in the present blood examination,among them,however,only one was perhaps related to the gamma knife treatment,and 5 oases had no complaints,and the other 3 displayed symptom and needed hormone replacement therapy,occupying percentage of 2.7%.Patients whose complaints disappeared completely or obviously accounted for 62.6%.showed slight or no improvement for 31.3%.and aggravated for 6.1%.Conclusions Gamma knife treatment for pituitary microadenoma showes affirmative efficacy,brings little trauma,has lower risk and less complication.It could be one choice of surgical therapeutic method for pituitary microadenoma.