Aspiration of foreign body is accidentally occurred and is most commonly encountered in children, although it is seen in patients of all age. It is not common in E.N.T. field but if occurred the diagnosis is almost depended on history of aspiration and emergency care with delicate operation technic is required as soon as possible. The authors made an analysis of 31 cases of foreign body in the air passage at E.N.T. department of Hanyang University Hospital from January 1973 to September 1981. That results were followings : 1) Sex distribution was male 3.4 as female 1. 2) Age distribution were 18 cases (58.0%) in 1-5 yrs., 6 cases (19.4%) in 6-10 yrs. and 4 cases (12.9%) in 11-15 yrs. in order. 3) Chief complaint was dyspnea in 22 cases(71.0%), coughing in 19 cases (61.3%) and cyanosis in 7 cases (22.6%). 4) Definite aspiration history of foreign body revealed 24 cases (77.4%) in diagnosis. 5) In physical examination there were decreased breathing sound in 20 cases (64.5%), wheezing sound in 9 cases (29.0%) and substernal retraction in 4 cases (13.0%). 6) Chest X-ray was revealed emphysema in 16 cases (51.6%), atelectasis in 11 cases (35.5%) and pneumonic infiltration in 3 cases (9.7%). 7) In duration of lodgement, it was most frequent within 1 day with 20 cases(64.5%). 8) In mode of treatment there were bronchoscopic removal under general anesthesia in 24 cases (77.4%), bronchotomy with open thoracotomy in 2 cases (6.5%), removal through the tracheotomy hole in 1 cases (3.2%) and removal under direct laryngoscopy in 4 cases (12.9%). 9) The nature of foreign body was revealed vegetable in 13 cases (41.9%), metalic in 7 cases (22.6%), plastic in 8 cases (25.8%) and fish bone in 3 cases (9.7%). 10) In lodging site of foreign body there were right main bronchus in 14 cases (45.2%), left main bronchus in 8 cases (25.8%), trachea in 5 cases (16.1%) and larynx in 4 cases (12.9%).