The adenotonsillectomy is common operation in otorhinolaryngology department because tonsil and adenoid hypertrophy produce frequent infection and nasal airway obstruction. The obstruction of nasal airway can cause snoring, mouth breathing, apneic attack, even cor pulmonale. From July 1994 to February 1995, 20 children who received adenotonsillectomy were evaluated using acoustic rhinometry and Wright mini flowmeter at preoperatively, postoperative 3rd days and postoperative 2nd weeks. The assessed parameters were the blockage index by Wright mini flowmeter and the cross-sectional area at adenoid and total nasal volume by acoustic rhinometry. We obtained the following results. 1) Blockage index was decreased at postoperative 2 weeks compared with preoperative value(p<0.05). 2) The cross-sectional area at adenoid and total nasal volume were increased postoperatively(p<0.05).