Abstract: In an endotracheal intubation method, during and after insertion of an endotracheal tube into a trachea of a patient, an image is transmitted along the endotracheal tube from a distal end to a proximal end thereof, thereby enabling an operator to determine proper placement of the endotracheal tube. The image transmitted from the distal end of the endotracheal tube may be automatically monitored by a computer. Upon determination that an incoming image is different from a stored reference image, an alert signal is automatically issued to an operator, thereby indicating that the distal end of the endotracheal tube has moved from a predetermined position within the patient's trachea. A desired image is selected upon insertion of a distal end portion of the endotracheal tube into a patient's trachea.