Background: To preliminarily evaluate the efficacy of Functional endoscopic sinus surgery (FESS) aided by a navigation system 3-dimensional imaging. Methols: A case series report of 9 patients who underwent FESS under the assistance of a navigation system in ENT department Khanh Hoa Hospital, 7/2010. Results: There were 9 patients ( 5 male, 4 female). Mean preoperative setup time and mean operative time were 12,5 + or - 2,57 minutes and 120,7 + or - 50,32. the mean number of sinuses operated on was 6,7 + or - 3,12. No complications were noted. Conclution: PESS with the assistance of a navigation system 3-dimensional imaging is an accuracy and safe way to treat patients with chronic sinusitis.