ObjectiveFunctioning pituitary macroadenoma and giant adenoma have large growth volumes and endocrinological abnormalities, requiring proper medical intervention. In this retrospective study, microneurosurgery and subsequent gamma knife radiosurgery (GKRS) is assessed for efficacy and safety for the treatment of functioning pituitary macroadenoma and giant adenoma. MethodsBetween January 2007 and December 2011, 59 patients with functioning pituitary macroadenoma (n=38) or giant adenoma (n=21) received microneurosurgical resection, and after three months, GKRS with average maximum radiation dose ∼42Gy (range 30–66.7Gy). The median follow-up time was 54.3 months (range 36–85 months). ResultsThe combined treatment controlled tumor growth in 81.4% (48/59) of patients, and improved the endocrinological status in 64.4% (38/59). Complications included hypopituitarism and visual deterioration (22 and 7 patients, respectively). Large tumor size at presentation was a risk factor for tumor recurrence, but not age, gender, invasion, radiosurgical dose, pituitary hormone status or follow-up period. Better outcomes were achieved by patients with macroadenoma than giant adenoma. ConclusionsCombined microneurosurgery and GKRS are safe and effective for functioning pituitary macroadenomas or giant adenomas. Tumor control and endocrinological improvement were satisfactory, with minimal complications.