AbstractFive APOB polymorphisms (I/D in the promoter region, XbaI [codon 2488], MspI [codon 3611], EcoRI [codon 4154], and 3 ´ VNTRs) were studied in a population sample of 147 healthy normolipemic Bulgarians. For all biallelic loci, the observed genotype distributions do not deviate from Hardy-Weinberg equilibrium. In Bulgaria the insertion allele and the MspI+ allele of APOB presented the highest allelic frequencies (0.793 ± 0.024 and 0.959 ± 0.012, respectively) among the European population groups studied so far. The allele frequencies of the other two biallelic polymorphisms (XbaI and EcoRI) found in the Bulgarian population are similar to those previously described in other Caucasian populations. Analysis of the 3 ´ VNTR polymorphism revealed 11 different alleles. Like studies in other Caucasian populations, this study found bimodal allele-size distribution and a high level of heterozygosity. The frequency of allele *31 (0.162 ± 0.022) among Bulgarians is higher than that of any other European population group studied so far. Genetic distances between Bulgarians and each of six populations from southeastern Europe for which 3 ´ VNTR allele frequencies are available showed an increase in the order: Albanians<Greeks<Slovaks<Croatians<Serbians<Hungarians. The major differences in the allele-size distributions are in the frequencies of alleles *31, *39, and *47.