It is important to identify relevant anatomical landmarks on the route of endonasal transsphenoidal surgery (TSS) for pituitary adenomas to improve the gross total resection and the remission of disease. We therefore retrospectively studied the clinical outcomes of 148 patients who underwent single nostril endonasal TSS for pituitary adenomas. The anatomic basis of these procedures was evaluated. The important landmarks included the mucosal sphenoid ostia, the sphenoid keel, the osseous ostia and the nutrient arteries nearby, the sellar bulge, and the carotid protuberance, which outlined a clear route to the sella turcica with the best view and less tissue damage. Based on these landmarks, 148 cases of endonasal TSS were successfully performed to achieve 70.3% of gross total resection and remission, respectively. The complications were controlled to the least. Therefore, the application of these landmarks will help to prevent complications and improve the long-term outcomes.