Inhaled anesthetics are inhaled via the lungs. They subsequently pass through the alveolocapillary membrane and diffuse into the blood to finally target the central nervous system and induce anesthesia. This principle of anesthesia induction was first described for diethylether in 1847. Nevertheless, the use of diethylether for anesthesia is obsolete and even the use of nitrous oxide (introduced for anesthesia in 1847) is declining in Germany. Almost all modern volatile anesthetics are halogenated methylethylethers in which fluorine is used as a halogen. All of these anesthetics depress myocardial contractility and induce hypotension. Depression of CO2 and hypoxia-induced respiration are other serious side effects. Further side effects are liver and kidney related but they are rare and not induced by anesthetics per se but preferentially by toxic metobolites. Another promising inhalative anesthetic is xenon which fulfils many aspects of an ideal inhalative anesthetic.