Study ObjectiveMeasure the displacements of endotracheal tube (ETT) tip displacement during head and neck movements. DesignObservational study. SettingEar-nose-throat (ENT) and neurosurgery operating room. PatientsWe performed a maximal head-neck movement trial on 50 adult patients, American Society of Anaesthesiologists 1 or 2. Patients with body mass index >35 kg · m−2, height <150 cm, airway malformations, pulmonary diseases, difficulties in neck flexion or extension, previous ENT surgery or radiotherapy, gastroesophageal reflux, or dental instability were excluded from the study. InterventionsENT and neurosurgery. MeasurementsWe measured the change in distance between the ETT tip and the carina, using a fiberscope through the ETT. ResultsAfter intubation, a wide disparity of tube tip distance to the carina in the neutral position was noted with a median of 5.0 (3.5-7.0) cm. Cephalad tube movement was documented following maximal head and neck extension in 34 (68%) patients and right head rotation in 25 patients (50%). Caudal tube displacement was due to maximal head and neck flexion in 38 patients (76%) and left head rotation in 25 patients (50%). Selective right main bronchus intubation was noted in 2 (4%) patients after maximal head extension. ConclusionMaximal head and neck movements led to unpredictable tube displacements. Proper reassessment of tube positioning after head and neck movement of intubated patients is therefore mandatory.