At elevations above 1500 m, even a healthy person undergoes acclimatization. To avoid problems such as acute mountain sickness (AMS), high altitude cerebral edema (HACE) or high altitude pulmonary edema (HAPE), the speed of ascent and the daily sleeping elevation are of primary importance. Mild symptoms and peripheral swelling are usually harmless. However, when the severity of altitude sickness progresses, rapid therapy and immediate transport to lower elevations can be life-saving under certain conditions. A sojourn in the mountains requires effective preparation and prophylaxis against oxygen deficiency, increased UV radiation, as well as against the possibility of hypothermia and frostbite.