The endoscopic transnasal approach is gaining increasing popularity as the surgical method of choice for treatment of pituitary lesions. Previous studies have shown advantages such as quicker recovery and fewer cosmetic, dental, and nasal complications. However, no study has compared the rate of diabetes insipidus (DI) between the traditional and endoscopic approaches. This study will examine the incidence of short- and long-term postoperative DI after transnasal pituitary surgery and compare it with the incidence after traditional transseptal surgery. Eighty-one patients underwent transnasal surgery for the management of pituitary lesions. Fifty-five had the traditional sublabial, transseptal, transsphenoidal surgery and 26 patients had the direct transnasal, transsphenoidal endoscopic procedure. The incidence of immediate postoperative DI was 36% in the traditional group and 15% in the endoscopic group. Short-term (>2 weeks) DI that required treatment occurred in 11 patients (20%) in the traditional group and 2 patients (7.6%) in the endoscopic group. Long-term (>6 months) incidence of DI was 7.2% in the traditional group and 3.8% in the endoscopic group. We found a decreased incidence of immediate DI after transnasal endoscopic pituitary surgery as compared with the traditional sublabial transseptal approach. However, the incidence of long-term DI was not significantly different in the two groups.