Haplotype analysis is considered a good method for studying the genetics of complex diseases while avoiding problems incurred by multiple testing. In this study, two haplotypes of E-selectin were significantly associated with essential hypertension. Moreover, a power analysis revealed that, for α = 0.05, our study had the power to detect differences across cases and controls of 0.93 for the A-carrying genotype of C602A, and 0.89 for the C-carrying genotype of T1559C. Furthermore, the distribution of all polymorphisms was in Hardy-Weinberg equilibrium (data not shown), suggesting that the results of this study are unlikely to be biased by population stratification or admixture for essential hypertension. Taken together, our data strongly suggest that C602A and T1559C are associated with essential hypertension. The potential mechanism by which the common SNPs (C602A and T1559C) might contribute to essential hypertension remains unknown. Because these two SNPs are located in exons and the variants exhibit changes in amino acidic residues, it is possible that the resulting proteins promote enhanced phagocyte and/or adhesive activity of the endothelium and provoke inflammation in the vascular wall--a characteristic of hypertension [17]. Endothelium damage and dysfunction and disturbance of endothelially derived vasomodulatory factors may be another explanation [18]. However, additional studies will be required.