Clinical symptoms that may require bronchoscopy include wheezing, hemoptysis and unexplained chronic cough. Roentgenologic findings that may be regarded as indications for bronchoscopy are obstructive emphysema, atelectasis, parenchymal densities of nonspecific character, abnormalities of the hilum or mediastinum, cavitation in the lung parenchyma, tumor like shadows in the lung parenchyma, pleural effusion of undetermined cause and the presence of an opaque foreign body. Bronchoscopy may be helpful for suitable specimens for biopsy, bacteriologic or cytologic study and removal of tenacious secretions. The authors have performed ventilating bronchoscopy and clinical analysis on 16 pediatric patients with intractable pulmonary diseases from September 1986 to March 1988. The results were as follows : 1) Among the 16 cases, 11 cases were male and 5 cases were female with the sex ratio of 2 : 1. Eight cases were under the age of 1. 2) By frequency of presenting symptoms and signs, coughing was the highest(87%), followed by fever(37%), dyspnea(25%) and wheezing(6%). 3) Duration of the symptoms before bronchoscopy was 8 days to 101 days(mean : 33 days). 4) Abnormalities in chest X-ray were noticed in 15 cases. There were 8 cases(50%) of atelectasis, 6 cases(37%) of pneumonia and one case(6%) of emphysema. 5) On bronchoscopy, there were 7 cases(44%) of abnormal bronchial secretions and 3 cases(19%) of redness and welling of the bronchial mucosa. 6) Bacteriologic study of the bronchial secretions revealed α-hemolytic streptococcus(10 cases), Neisseria(3 cases), non-hemolytic streptococcus(2 cases) and so on. 7) There was improvement of clinical symptoms in 13 cases with medications. We conclude that bronchoscopy will be available for diagnosis and treatment in patients with intractable pulmonary diseases.