Densitographic examination of the regional pulmonary ventilation is a non-pretentious and non-invasive method which can be used even in very young children, which when aspiration of a non-contrasting foreign body is suspected can confirm by revealing localized bronchial obstruction the presence of a foreign body and determine its localization in the tracheobronchial tree. By repeated records of adequate ventilation at rest in all pulmonary fields it is possible with a minimal radiation load to rule out the suspicion and the child need not be subjected to an endoscopic examination. In five children aged 19 months to 13 years the usefulness of this procedure for the diagnosis of aspiration of a non-contrasting foreign body was proved, as the physical and skiagraphic finding was not convincing, there was discrepancy of anamnestic data and results of repeated skiagraphic examinations, negative auscultation and negative X-ray examination after an anamnestically obvious cse of aspiration, it ws used, for a more accurate localization of the aspired object, and to confirm localized obstruction of pulmonary ventilation in a chronic foreign body of plant origin in the airways. Foreign bodies of plant origin, most frequently aspired by children, are dangerous because they are fragile, swell and exert toxic action on the bronchial mucosa and there is also the danger of rapid development of serious bronchopulmonary complications. Therefore early diagnosis of aspiration is essential in these frequently obscure situations. When the direct skiagraphic signs of their presence in the lower airways are lacking dynamic pulmonary densitography contributes greatly to the diagnosis.