To report the value of nasal endoscopy as an outpatient procedure in the diagnosis of posterior nasal obstruction.Over one year period, from March 2002 to March 2003, we evaluated 130 adult patients that attended the Ear, Nose and Throat Department of Sohag University Hospital in Egypt with persistent nasal obstruction via anterior rhinoscopy and flexible nasopharyngoscopy. We reported the cause and site of obstruction in relation to the choanae. We confirmed the diagnosis by CT scanning, rigid endoscopic examination under general anesthesia, and histopathological analysis of biopsies taken.Forty-six percent of our cases had posterior nasal obstruction, 43.5% due to post-choanal lesions (mainly adenoid), 33% due to pre-choanal lesions (mainly choanal polyps), and 23.5% due to choanal lesions (mainly choanal adenoid).We conclude that flexible nasal endoscopy is superior to visual examination in the evaluation of nasal obstruction; hence, we recommend its routine use.