Adenoid vegetation is the most common cause of the upper airway obstruction in pediatric patients, There has been many methods to assess the adenoid size but no definitely accepted objective criteria for adenoid vegetation was made. We used the nasal endoscope to assess the adenoid size, residual nasopharyngeal airway and the condition of the eustachian tube orifice, then we compared these assessments with clinical symptoms, tympanogram and lateral neck radiograph. The authours concluded as follows : 1) The endoscopic types of adenoid were highly correlated with clinical symptoms and tympanograms(p<0.05). 2) The endoscopic examination of the adenoid and the condition of eustachian tube orifice provided informations about the causes of clinical complaints and specific site of lesion. 3) The lateral neck radiograph was not a accurate method for the evaluation of the adenoid vegetation.