On the basis of 11,280 marriage records of four regions of Karachay-Cherkessia (Karachaevsky, Malokarachaevsky, Ust-Dzhegutinsky, Prikubansky, 193.2 thousand people in total) for 1990-2000, the intensity of Karachay cross-breeding was determined, amounting to 11.7%. Comparison of the intensity of Karachay cross-breeding with that for some other ethnoses is carried out. The ethnic assortativness H is approximately one. The population is characterized a preference for monoethnic marriages. The endogamy index in the studied regions varies from 0.29 to 0.53; after the exclusion from the analysis of repatriates, it increases to 0.34-0.63. The values of local inbreeding in an interval are 0.0001-0.0004, and no differences in terms of isolation by distance are revealed among the regions (0.01). The average square migration is 40-60 km.