Abstract We retrospectively analyzed surgical outcomes of transsphenoidal surgery for pituitary adenomas. A total of 366 consecutive patients undergoing transsphenoidal surgery for a pituitary adenoma from December 1990 through May 2017 were included in this study. The most common tumor type was nonfunctioning pituitary adenoma (NFPA) (63.7%), followed by prolactin-secreting adenoma (20.5%), growth hormone-secreting adenoma (13.4%), adrenocorticotropin-secreting adenoma (2.2%), and thyrotropin-secreting adenoma (0.2%). This cohort study consisted of 164 male and 202 female patients. The median patients age was 48 years. The median follow-up duration was 63 months. Gross-total resection (GTR) was achieved in 83.7% of patients with a NFPA, 76% of prolactin-secreting adenomas, 71.4% of growth hormone-secreting adenomas, 75% of adrenocorticotropin-secreting adenomas, 100% of thyrotropin-secreting adenomas. There were 326 macroadenomas (69.1%). Surgical outcome was better in patients with microadenomas than in patients with macroadenomas (100% and 77.9%, respectively). Improvement of visual disturbances occurred in 148 (93.7%) of the 158 cases. Hormonal impairment by pituitary adenoma was improved in 105 (87.5%) of the 120 cases. There were 24 (8.2%) cases of recurrence after GTR; 17 patients underwent second surgery, 5 patients received radiotherapy, and the others continued conservative treatment. The median time interval between TSA and recurrence was 56 months. Postoperative cerebrospinal fluid leakage occurred in seven (1.9%) of 366 patients. Transsphenoidal surgery is an effective and safe treatment modality for most patients with pituitary adenoma.