Abstract: An esophageal intubation detector with an indicator is used to determine whether the hollow tip of an endotracheal tube is in the esophagus or trachea of a patient. In a preferred embodiment, the esophageal intubation detector includes a syringe (or a bulb) connected to the endotracheal tube through an adapter to which the indicator is connected. The bulb may be associated with a resuscitator bag. A clinician places the endotracheal tube into, for example, a patient's mouth and throat. The esophageal intubation detector is connected to the endotracheal tube creating a system. The system volume increases through retraction of a syringe plunger or self-inflation of a depressed bulb. If the tube tip is in the esophagus, the tube tip will become occluded with the walls of the esophagus as the system volume increases, causing the system pressure to decrease and causing activation of the indicator, implying that the endotracheal tube is in the esophagus.