Object: To estimate the efficacy of Gamma Knife radiosurgery (GKR) especially as a primary surgical treatment for hypersecreting pituitary adenomas. Methods: 274 patients were treated with GKR. The mean tumor volume was 1.86 cm3. The mean peripheral dose was 28.7 Gy. Results: 223 patients were followed up for an average of 31.6 months. The dose related to the tumor growth control and endocrinological normalization was detailed and statistical analysis of the data was performed. Conclusion: GKR as a primary surgical treatment for hypersecreting pituitary adenomas may be safe and effective.