A total of 12 Transbronchial Biopsies (TBB) were performed in pediatric patients during the last year at the Hospital Universitario San Ignacio, using an adult small bronchoscope (5.3 mm outer diameter Olympus). Results: In 9 patients adequate lung tissue for histological diagnosis was obtained. In two patients with HIV infection, respiratory symptoms and chest x-ray abnormalities, pathogens were identified and successfully treated: positive ZN (13 y.o. female) and P. Jiroveci (12 y.o. female). Several patients presented with dyspnea and mosaic patterns in the chest x-ray: in three cases the information was useful, and all of them improved after treatment. 12 y.o.male in whom lung metastasis were found (successful chemotherapy initiated), 14 y.o. male in whom capillaritis was found (improvement after treatment). In an 8 y.o. male insufficient sample was reported. In patients with malignancies, useful information was provided: in patients with lymphomas and lung infiltrates CMV was identified and treated (10 y.o. male) and P. Jiroveci was found in two patients with leukemia. The only complications were a small pneumothorax that did not require intervention and hypotension in a septic HIV patient that was sent to Intensive Care for management. Conclusion: The Transbronchial biopsie is an effective and safe procedure to obtain lung tissue for histologic diagnosis in a variety of conditions such a tumors, infections or pulmonary infiltrates and that can be considered as first –line diagnostic procedure in pediatric patients. References. 1. Visner GA, Faro A, Zander DS. Role of transbronchial biopsies in pediatric lung disease.Chest 2004; 126:273-280.