Relative incidences of esophagus, lung and breast cancers differ in the various populations in Kyrgyzstan.Esophagus cancer is the most commonly observed among the Turkic groups, especially in Kazakhs, while lung andbreast cancer are frequently encountered among the European representatives of the population – Russians inparticular. Fluctuation in rates for these cancer forms in the Kyrgyzstan mountain regions is highly dependable onthe height above sea level. One potential major factor, which may account for the low cancer frequency in generaland influence esophagus, lung and breast cancer forms in particular – is mountain hypoxia. Since, among the nativecitizens (Kyrgyzes), which are adapted to mountain hypoxia conditions (population adaptation), the indicated cancerforms are not so often than the same forms appearance among the other ethnical groups (long adaptation), especiallynewcoming ones.Thus, the incidence rates of esophageal cancer in the Kazakh population is about 32,3 (per 100,000), the samesickness in Kyrgyz is about 11,3, the figure for lung cancer among the Russian population is 34,8, while amongKyrgyzes it is 11,2, breast cancer incidence in Russian citizens is 34,8 but only15,1 among Kyrgyz residents.It could be established that the studied forms of cancer are less common in high mountain regions than in theregions with low mountains. To a certain extent, mountain hypoxia may function like a brake for the development ofcancer tumors. HGowever, the situation is complex, because of , the presence of the other factors entailed by thedemographic, social-economic and other variation.