Until recently animals inhabiting mountain areas were relatively free from disturbance by people but they are now coming under increasing pressure. Tourism, especially that involving large numbers of people, is having an ever more detrimental effect on the natural resources of high mountains, even in protected areas. We analyse the effect of tourist pressure on the population of the Tatra chamois Rupicapra rupicapra tatrica, which inhabits the strictly protected high-altitude habitats of the Tatra mountains (Carpathians, Poland). The Kasprowy Wierch cable car system, in operation since 1936, was modernized in 2007; as a consequence 50% more people can now be carried into the chamois’ habitat. The effect of this sudden increase in tourist pressure has been to reduce the size of herds (3.9 vs 5.3 individuals) and to increase the distance between the animals and the cable car station (1,664.0 vs 693.0 m), the cable car infrastructure (1,415.0 vs 467.8 m) and adjacent ski-lifts and ski pistes (1,214.2 vs 494.3 m). The distance to the marked hiking trails has not changed, however. Following the modernization of the cable cars, larger herds of chamois have been seen at greater distances from the tourist infrastructure. Our results indicate the adverse impact of this mass tourism. Human activities in high-mountain ecosystems need to have due consideration for the requirements of wild species, and the number of visitors needs to be controlled.