We studied the possible effects of climatic factors on the world distribution of alleles determining alpha 2-HS-glycoprotein (AHSG) phenotypes in human populations. New data on AHSG polymorphism in certain ethnic groups of Russia are presented. All available data on the distribution of AHSG gene frequencies in the world (number of populations n = 51) were used to analyze possible correlations between AHSG*2 allele frequencies and seven climatic-geographic parameters. A strong positive correlation was found between AHSG*2 allele frequency and geographic latitude of territories inhabited by the study populations (r = 0.814). The dependence of the AHSG*2 allele distribution in the world on the intensity of ultraviolet radiation (400-315 nm) was estimated at r = -0.826. Such climatic characteristics as the total amount of insolation and the average annual temperature proved to make equal contributions to variation in AHSG*2 allele frequency (r = -0.683 and -0.658, respectively). A computer cartographic model of the AHSG*2 allele distribution in the Old World populations of the Northern Hemisphere was constructed.