Disorders of water metabolism are a common complication of pituitary surgery. The primary purpose of this study was to determine the incidence and duration of post-surgical diabetes insipidus (DI) at our institution. Secondary objectives included characterizing the incidence of post-operative hyponatremia as well as delineating factors associated with the onset of these complications. Records of 319 patients who underwent transsphenoidal pituitary surgery at the authors' institution between 1998 and 2005 were reviewed for the presence of disorders of water metabolism using pre-specified criteria. DI was diagnosed in 59 (18.5%) of our patients at a mean time of 13.6 h following surgery. DI resolved in nearly half of our patients within one week. Approximately 80% of our patients enjoyed resolution of DI at a mean time of 2.9 months following surgery. Duration of DI was not significantly influenced by tumor size or location. Additionally, 28 (8.8%) of our patients exhibited a period of hyponatremia at a mean time of 4 days following surgery. One quarter of these patients carried a diagnosis of Cushing's disease. We herein report an incidence of DI as well as hyponatremia within our post-operative population comparable to that reported by other high-volume pituitary centers. Over half of our patients still exhibited DI at the time of discharge, therefore, patient education regarding the treatment of DI, signs of its resolution, and symptoms consistent with the onset of hyponatremia should be an integral part of every hospitalization.