Pedigree samples were collected from five ethnically and geographically different populations: Kirghizians, Turkmenians, Chuvashians, Israelis and Mexicans. All studied individuals were assessed for body height, weight and BMI. The sample size in the studied pedigrees ranged from 381 to 1811 individuals. Segregation analysis of these traits preliminarily adjusted for sex and age was performed by means of program package MAN that provides parameter estimates for the major gene effects, for the residual within the genotype correlations between relatives and for the assortative mating. By the usual transmission probability tests, the ‘environmental’ model was strongly rejected for all measured traits in all 5 populations. The major gene mode of inheritance, however, was accepted for all traits. The results of analysis in 5 populations were remarkably similar, and showed that except for Mexican sample, the proportion of variance attributable to major gene effect ranged between 37 and 53% for body weight and height. In the Mexican sample it explained only about 14% of the body weight variation. The proportion of inter-individual variation in BMI attributable to major gene effect was consistently lower in all populations in comparison with height and weight and ranged between 17 and 40%. Strong assortive mating in body height, as estimated by correlation between putative major gene genotypes in spouses, was found in four populations, not including Mexican pedigrees.