Improvements in surgery have focused on refinements in the ability to dissect and limit blood loss. The electrosurgery unit (ESU) and laser (light amplification by stimulated emission of radiation) have been widely used in recent endoscopic surgery. ESU is a form of surgery in which high-frequency (100 kHz-5 MHz) electric currents are used to incise, destroy, and remove tissue and to seal blood vessels in order to maintain hemostasis. The use of lasers in surgery has added a new dimension to operative technique through increased precision, improved hemostasis, and less tissue manipulation. This paper aims to explain the basic principles and applications of electrosurgery and lasers.