The interleukin-1beta (IL-1beta) is an important pro-inflammatory cytokine in a broad spectrum of physiological processes. Previous investigations have observed that levels of the IL-1beta were higher in essential hypertensive patients and the IL-1beta gene polymorphism has been shown to be related to IL-1 production. We hypothesized that genetically determined differences in activity or responsiveness of cytokine(s) might contribute to hypertension. In this report, we utilized a family-based design to test the association between the IL-1beta C(-511)T polymorphism and blood pressure levels in hypertensive patients chosen from rural communities in Anhui, China. In men, carriers of the IL-1beta (-511)*C allele were found to have lower systolic (P = 0.049) blood pressure levels compared with T homozygotes, which conforms to an additive effect model. By contrast, no significant association between the IL-1beta gene and blood pressure levels was revealed in women. Our results suggested a significant role of the IL-1beta C(-511)T polymorphism in the control of blood pressure in Chinese hypertensives.