Abstract： Objective To analyze the transsphenoidal microsurgical effect of Cushing's disease. Method The clinical data of 541 Cushing's disease cases were analyzed retrospectively in this study from 1981 to 2007. Results CT/MRI revealed microadenoma in 358 cases (66.2％ ), macroadenoma in 76 ( 14.0％ ) ,huge adenoma in 3 ( 0.6％ ) and negative results in 104 ( 19. 2％ ). Pathological examination confirmed pituitary ACTH adenoma in 408 ( 75.4％ ), pituitary ACTH cell hyperplasia in 45 ( 8. 3％ ), no evidence of adenoma or hyperplasia in 88 ( 16. 3％ ). In our group, the cure rate were 85.0％ ( 347/408 ),24. 4％ (11/45) and 45.5％ (40/88) respectively in Cushing's disease patients with pituitary ACTH adenoma, pituitary ACTH cell hyperplasia and negative pathological results. The follow up period ranged from half year to 25 years( average 3.1 years). Recurrence rate was 13. 3％. Average recurrent time was 3.4 years (0.5 - 16.5 years ). Conclusions Transsphenoidal selective adenomectomy plus resection of parsadenomatous pituitary tissue is the first choice in the treatment of Cushing's disease. Repeated transsphenoidal pituitary surgery or pituitary radiotherapy could be underwent for patients after failed surgery of recurrenct cases.