The apolipoprotein H (apo H) is a constituent of several lipoprotein particles and, therefore, may play an important role in lipid metabolism. In this study, we have investigated the role of common apo H structural polymorphism in determining serum total cholesterol; high-density lipoprotein cholesterol; triglycerides; and apolipoproteins A-I, A-II, and B in 655 Chinese and 126 Dravidian Indians from Singapore. Serum lipoprotein and apolipoprotein levels were adjusted for significant concomitant variables for age and body mass index, and the quantitative mean values between different apo H genotypes were compared by an analysis of covariance. The distributions of serum lipoprotein and apolipoprotein levels were found to be comparable between the three common apo H genotypes in both ethnic groups, indicating that the apo H polymorphism may not play a significant role in lipid metabolism.