The effect of a DNA polymorphism (Mspl) of the apohpoprotein (apo) A-II gene on serum lipid and apo levels was studied in a group of 125 healthy Chinese of both sexes. The frequency of the 3.7-kb rarer allele (M2) was found to be significantly higher in the Chinese (0.30) than in Caucasians (0.16; p < 0.025). The distribution of apo A-II genotypes was in Hardy-Weinberg equilibrium in the Chinese population. The presence of a polymorphic site (Mspl) within an Alu sequence at the 3’ end of the gene, the 3.0 kb (M1)allele, was associated with significantly higher levels of serum apo A-I and A-II (p < 0.05 and < 0.01, respectively). Serum high-density Lipo-protein cholesterol levels were also correspondingly higher in individuals with M1, but did not reach a significant level. Male heterozygotes of the apo A-II polymorphism had significantly higher levels of serum triglycerides compared to homozygotes (p < 0.05). Thus the Mspl polymorphism of the apo A-II gene appears to be associated with altered levels of lipids and apos in the Chinese populatio