The utility of a neuronavigation system in the transsphenoidal surgery of pituitary macroadenoma was evaluated, and improvement of the surgical outcome is discussed. From 1997 to 2003, a total of 63 patients (male:female=41:22, mean age 58.3 years) with pituitary macroadenoma were treated surgically via transsphenoidal approach using a neuronavigation system in Beijing Tiantan Hospital. Image data for computed tomography or magnetic resonance were obtained and analyzed by the navigation system to make a three-dmensional reconstruction. During the operation, the tumor and its surrounding structures of the sellar region could be located accurately at any time. Among these cases, the tumors were removed totally in 26 cases (41.3%), subtotally in 36 cases (57.1%) and partially in one case (1.6%). Postoperative neurological complications occurred in 15 cases (23.8%). One patient died, the operative mortality was 1.6%. During the operation, the accuracy of the neuronavigation system was 2.3 +/- 1.1 mm. The neuronavigation system is quite helpful for transsphenoidal surgery of pituitary macroadenoma. Its accuracy of location is very useful and important in determining anatomical structure and protecting normal tissues and vessels. Moreover, fluoroscopy was not required during the surgery.