Diagnostic difficulties and causes of incorrect interpretation of bronchoscopic examination in the cases of foreign body (f.b.) aspiration in children are presented. In 16 out of 280 children (5.7%) treated in our Institute due to f.b. aspiration in the years 1979-1993, f.b. were not diagnosed (incorrectly excluded or not confirmed) although bronchoscopic examination have been performed. Recurrent or persistent symptoms of bronchitis or bronchopneumonia were indications for performing diagnostic bronchoscopy in our hospital. The causes of diagnostic difficulties during the first bronchoscopy were as follow: 5-most likely inflammation, 2-peripheral deposition of foreign body, 2-only tracheoscopy was performed. In 7 cases the lack of necessary technical competence for performing bronchoscopy was probably the cause. Foreign bodies were deposited in 2 cases in the trachea, in 4 cases in the right bronchial tree and in 10 cases in the left bronchial tree. One child with diagnostic problems is describe in details. We have found that: -for exclusion of f.b. aspiration detailed examination of segmental or even subsegmental bronchi is necessary, -diagnosis and treatment of f.b. aspiration requires good bronchological knowledge and experience, -persistent symptoms of bronchial patency disturbances should be the indication to the control bronchoscopy.