There is an accumulating body of evidence indicating that inflammation plays a pivotal role in the pathogenesis of cardiovascular disease. Interleukin-6 (IL-6) is a pleiotropic cytokine secreted by many cells of the immune system, cardiovascular components and adipose tissue, and functions as a mediator of inflammatory response with both pro- and anti-inflammatory properties. Circulating levels of IL-6 differ greatly between individuals due to both genetic and environmental factors. The IL-6 -634C>G polymorphism is common in eastern Asian populations. The aim of the present study was to investigate the association of this polymorphism with essential hypertension (EH) and left ventricular hypertrophy (LVH) in 440 subjects (246 EH patients and 194 controls) from a Han Chinese population. In this study, IL-6 -634C>G genotypes were identified by polymerase chain reaction and restriction digestion in all study participants, and left ventricular mass was assessed by 2-mode echocardiography in 178 untreated EH patients. There was no significant difference in either genotype distribution (p=0.9528) or allele frequency (p=0.7775) between the EH and control groups. In addition, the -634C>G polymorphism had no effect on blood pressure in either the controls or the untreated EH patients. No significant differences in genotype distribution (p=0.7998) or allele frequency distribution (p=0.5468) were found between EH patients with and without LVH. Moreover, the echocardiographic parameters were not statistically different between the CC and CG+GG genotypes. These findings suggest that there is no association of the IL-6 -634C>G polymorphism and EH with LVH in EH patients.