Patients with Turner's syndrome present a multiplicity of cardiovascular and airway abnormalities. We describe a case of Turner's syndrome with pericardial effusion who experienced an inadvertent endobronchial intubation due to displacement of the endotracheal tube immediately after the pericardial drainage. A sudden increase of airway pressure and decrease of oxygen saturation in the presence of breathing sound audible via the chest piece placed on the left hemithorax first misled us to call our attention to sputum impaction. No sputum was obtainable from airway suction. Inadvertent bronchial intubation was highly suspected at the post-anesthesia room when a decrease of right side breathing sound was noted together with a progressive fall of oxygen saturation. Emergent chest x-ray confirmed the diagnosis. It was thought that the mishap took place early in the act of or following the pericardial drainage. Our case serves as evidence once again to emphasize the possibility of endobronchial intubation due to displacement of endotracheal tube during anesthesia and the importance of monitoring to guard against inadvertent bronchial intubation, particularly in patients with associated problems such as Turner's syndrome with huge pericardial effusion.