The endoscopic endonasal transsphenoidal approach through the bilateral nostrils was evaluated for the treatment of pituitary adenoma. The surgical approach is through the bilateral nostrils via minimal or wide dissection of the septal mucosa, depending on the degree of tumor extension. After anterior sphenoidotomy, the endoscope is fixed in one nostril and required instrumentation is inserted in either nostril. In addition, neuronavigation and real-time hormone monitoring are used. Tumor removal rate, endocrinological outcomes, and complications were retrospectively assessed in 194 patients with pituitary adenomas who underwent 213 procedures between December 2001 and March 2008. Greater than 95% resection was achieved in 74 of 131 nonfunctioning adenomas, and the removal rate was significantly higher during 2005-2008 compared to 2002-2004 (p < 0.05). Endocrinological remission was achieved in 20 of 26 growth hormone-secreting tumors of Knosp grades 0-2, 16 of 17 microprolactinomas, and 6 of 9 cases of pure Cushing’s disease. Postoperative complications were cerebrospinal fluid leakage in 9 cases, visual worsening in 5, anterior pituitary insufficiency in 5, and permanent diabetes insipidus in 2. The bilateral endonasal approach provides a wide working area without the need for special instrumentation. By modifying mucosal dissection, the endoscopic approach provides flexibility and less invasiveness. The use of neuronavigation or intraoperative hormone monitoring leads to improved surgical results. The present study confirms that this approach is suitable for more extensive sellar tumors.