The endothelial isoform of nitric oxide synthase (eNOS) is responsible for the physiological production of NO in endo-thelial cells and platelets. There is evidence that the G894T polymorphism of the eNOS gene is associated with this enzyme's basal activity and NO production, which could contribute to the pathogenesis of periodontal diseases (PD). Therefore, this study was designed to investigate the role of G894T polymorphism in the eNOS gene as a predisposing factor to periodontal disease. In this study we investigated the association of this polymorphism with PD in an admix-ture population (N = 119) separated into three groups: Healthy control, Moderate and Severe PD, without statistical differences among them for risk factors for PD, such as age, gender and smoking status. We observed that the GG ge-notype was associated with the progression of PD as indicated by an increase in frequency of approximately 18% in the Moderate and 26% in the Severe groups compared to the Healthy control group (p = 0.0302). This finding indicates that patients carrying the GG genotype have a greater chance of developing PD compared with those carrying the T allele, and it reinforces the notion that genetic factors contribute to the development and aggravation of PD.