(Uploaded by Plazi for the Bat Literature Project) The occurrence of bats in mountains at high altitudes above 2300 m has not been investigated in the Alps until recently. In other European mountains, only a few studies on bats in high regions e.g., in the Pyrenees or in Switzerland at the Col de Bretolet had been conducted. Here we report a study carried out between 2012 and 2016 at several high-alpine sites at altitudes ranging from 2250 m up to 2761 m in the mountains of the Hohe Tauern, Salzburg, Austria. In spite of extreme climatic conditions, a surprisingly high bat activity and diversity of bat species was recorded. Eleven bat species were detected by different methods. Species identified by echolocation calls were: Barbastella barbastellus, Eptesicus nilssonii, Nyctalus noctula, N. leisleri, Pipistrellus pipistrellus, P. pygmaeus, Myotis daubentonii, and Vespertilio murinus. Additional findings were the species pairs Myotis mystacinus/M. brandtii and Pipistrellus nathusii/P. kuhlii as well as the genus Plecotus. The presence of most of these species was confirmed by capturing individuals with mist nets. Permanent monitoring of ultrasound calls was undertaken throughout the active period of bats at the site located at 2315 m above sea level. A total of over 30,000 series of bat calls were recorded and the activity period lasted from the end of March to the beginning of November. Long-distance migratory bat species were recorded in spring under wintry conditions and much more prominently from August to October. Presumably these individuals were crossing the Alps on their way between summer and winter roosts. Sedentary bats used the high alpine zone for foraging during summer. At these altitudes bats were active at high wind speeds of up to 13.9 m/s as well as at low temperatures around freezing point and down to -5.8°C.