Background: Preoperative airway assessment should be performed routinely to identify factors that lead to anticipate difficulty with face-mask ventilation, a supraglottic airway device insertion and tracheal intubation. Difficult airway can be divided into difficult Supraglottic Airway (SGA) placement, difficult mask or SGA ventilation, difficult laryngoscopy, difficult or failed endotracheal intubation. Difficult ventilation is defined as the inability of a trained anesthesiologist to maintain oxygen saturation >90% using a face mask, with a goal of oxygen fraction of 100 %. Difficult intubation is defined as the need for more than three attempts for intubation of the trachea or more than 10 min to achieve it, a situation that occurs in between 1.5 and 8% of general anesthesia procedures. Because inadequate airway management continues to be an important contributor to serious complication, ultrasound is an emerging tool that has many obvious advantages (safe, fast, repeatable, portable, widely available, and gives dynamic images in real time) that we can use for patient safety. Accurate interpretation of US images requires a basic understanding of the physical principles involved in US image generation. In addition, transducer selection, orientation and anatomy of airway relevant to US imaging is important to evaluate anatomy of the airway. US is the acoustic frequency above the threshold for human hearing (20 kHz). In medical practice, high‑frequency pulses of sound waves are used (2.5–10 MHz). The probe that generates this wave contains material that produces piezoelectric effect. Lower the frequency, higher is the penetrance of tissues but lower is the potential image resolution. Depending on the shape and configuration of the probe, different shaped fields of view are generated. Two types of probes commonly used are linear and curved. Standard 7.5 MHz linear probe and 5 MHz curved array probe are commonly used for visualization of superficial and deeper structures of the airway, respectively. Reflection, refraction, scatter, absorption and transmission of sound occur as it passes through soft tissue structures, allowing characterization of the shape and internal architecture of that structure in addition to those behind it. Reflection of sound is marked at interfaces between tissues of different acoustic impedance. The image is built from the reflected sound signals.