In this paper,the allelic distributions of apo B gene 3'-variable number of tandemly repeat(VNTR)in Chinese Han and Mongolian nationalities were alalyzed by PCR techniqe. The nucleotide acids of HVE34 and HVE46 were sequencied by automatic Ma chine AB1373A Model.The results showed that 14 al leles in the samples of 300 Han individuals(164 cases of patients with coronary heart disease and 134 normal matched subjects) and 12 alleles in the samples of 61 Mongolian individuals. In Han nationalit y group,the most common allele is a repeat unit allele (HVE36),occupied 31% of the total alleles. HVE34 and HVE32 are 24%and 22%respectively. In comparison with Han nationality,the most common allele in Mongolian nationality group is HVE34,occupied 35.2%. HVE36and HVE32 are 28.7%and 13.9%respectively.Futhermore,we also found that the alleles of homozygote(80%)in Mongolian group are much higher than that(52%)of Han nationality group. No alleles less than HVE30 was found in the Mongolian group. The amplication products of homozygotes of HVE 34 and HVE46 alleles were directly aequenced. It was found that the 3' hypervariable region apo B gene consists primarily of a 15 bp basic repeat unit called X and Y sequence and tandemly repeat in an X-Y Order. The ATrich region also contains variants of X and Y sequences resulted from C or G for A substitution. The length of different alleles was ditermined by the numbers of X and Y copies. The HVE polymorphism of apo B gene not only resides in the variable numbers of repeat units,but also resides in the variation in the oligonucleotide sequence within the repeat units as well as the variation in the arrangement of the repeat.