This chapter discusses laser in head and neck cancer, where physical properties of lasers are based on the active medium, which represents the first major component of all lasers and may be in a liquid, solid, or gaseous phase. Examples of solid-state lasers include the neodymium: yttrium–aluminium–garnet (Nd: YAG) laser, and semiconductor or diode laser, where common gas lasers include argon, carbon dioxide (CO2), and helium–neon. The wavelength of the laser beam is related to the active medium and must be taken into account when selecting a laser for a specific function. During any surgical procedure employing laser devices, special care must be given to the use of anti-ignition endotracheal tubes with a double cuff, intraoperatively protected by wet sponges. One of the most striking advances for treatment of glottic cancer is the possibility of performing endoscopic laser-assisted partial cordectomies instead of standard total cordectomy as those allowed by traditional open-neck approaches.