The field of application for fibreoptic bronchoscopy (FB) in the intensive care unit has been extended since the generalised introduction of fibroscopes of 4.9 mm in diameter (previously called paediatric fibroscopes). Paediatric and neonatal intensive care units have benefited from the availability in the market of these small endoscopes for 3.5 and 2.2 mm. The protected brush and alveolar lavage (LBA) enables a specific diagnosis to be made in bacterial pneumonia acquired during ventilation. The sensitivity of these techniques however is insufficient to be able to recommend their use as routine. Inversely, the FB with LBA remains a fundamental feature in the diagnosis of opportunistic infections in pneumonia. For the treatment of atelectasis, FB is overall not superior to physiotherapy. Aspiration with a fibroscope can however be recommended straight away in cases of alteration in blood gasses if cough is ineffective or if the atelectasis complicates endobronchial bleeding. The FB enables problems with difficult intubation to be resolved or for the positioning of probes. The conditions under which this is performed are more delicate than in routine anaesthesia (in cases of urgency, hypoxia). In the case of respiratory burns, tracheobronchial fracture and post intubation stenosis, FB enables both the diagnosis to be established and the level at which the lesion occurs. In paediatric intensive care, a fibroscope of 3.5 mm is used for performing LBA (opportunistic pneumonias), difficult intubation (facial dysmorphia), endoscopic diagnoses, in particular where there is a suspicion of an endobronchial foreign body, the assessment of unexplained dyspnoea (tracheal stenosis by vascular ring) and obstructive lesions. In neonatal intensive care, a fibroscope of 2.2 mm is used for difficult intubation and the localisation of lesions induced by ventilation.