Electrosurgical instruments are routinely used in many applications by the surgeon. In principle, high-frequency electrical currents are used by passing trough tissue for cutting and coagulation. The heat generated by the electrosurgical unit is proportional to the resistance and diameter of the tissue. There are two commonly used electrosurgical modalities: monopolar and bipolar. Since negative side-effects of electrosurgery are possible (e.g. burn, interaction with other electric devices) a proper knowledge of all staff involved in electrosurgery is warranted. In the context of a safe perioperative patient management the anesthesiologist should know basic principles of high-frequency surgery as well. This article describes the main aspects of electrosurgery for anesthesiologists.