A distal bronchial brushing was performed in 25 children having severe lung diseases. The age of the patients ranged from 7 days to 14 years. Seventeen children were immuno-depressed. Bacteria were isolated five times (2 Staphylococcus aureus, 1 Streptococcus pneumoniae, 1 Serratia marcenscens, 1 Acinetobacter lwoffi), viruses twice (cytomegalovirus, syncytial respiratory virus), Pneumocystis carinii, four times. Cytologic study revealed malignant cells, and cells with intranuclear inclusions, evoking a viral infection. This procedure appears to be harmless in children over 2 years of age. In younger children there is a risk of pneumothorax. the principal indication for distal bronchial brushing is lung disease in immuno-depressed children. It may, however, also be useful in prolonged, treatment-resistant, severe lung diseases.