Abstract: Given is data concerning disease (sarcoptosis) of Siberian ibex (Capra sibirica) in Western Tien Shan. The carriers of the disease are adult males of Capra sibirica during distant migrations that as a rule take place in anticipation of snowy winters or owing to human influence. Ibexes are not merely infected with sarcoptosis but perish enmasse from the disease. In the first year the disease strikes down, in the main, migrants – adult males. Predators including snow leopard kill the weakened animals. During the recent five years the density of Carpa sibirica at the Chatkal Mountain-Forest Reservation dropped 2.3-fold as a result of sarcoptosis and owing to the migrations caused by the reduction of the population. Is recommended: 1. Stringent veterinary control at places of possible contacts between infected domestic animals and healthy wild ungulates. 2. Using modern technology migration routes of ungulates should be studied for elaborating effective measures of quarantine.