Periodontal disease is a common oral disease. Inflammatory and immune responses to oral microorganisms initiate the development of periodontitis. Cigarette smoking is an important environmental risk factor for periodontitis. Another important inflammatory mediator is nitric oxide (NO). NO modulates vascular tone, microvascular permeability, leukocyte migration and oxidative activity, contributing to the direct killing of microorganisms. Several polymorphisms of the NOS3 gene have been detected, which may alter gene expression and NO synthesis. The aim of this study was to examine the association between the NOS3 rs1799983 and rs2070744 polymorphisms and periodontal disease. This study enrolled 200 patients with periodontal diseases (130 were non-smokers and 70 were smokers) and 160 control subjects (126 were non-smokers and 34 were smokers). Among the patients with periodontal disease, we observed a statistically increased frequency of patients with the CT genotype (TC vs. TT; 95%CI 1.83, OR 1.16–2.88, P = 0.011). There was a statisti-cally significant increased frequency of CT genotype carriers among non-smoking patients with periodontal disease as compared with non-smoking controls, whereas there were no statistically significant differences between smoking patients with periodontal disease and smoking control subjects. The results of our study suggest an association between the NOS3rs2070744 polymorphism and periodontal disease. and Corresponding author: Andrzej Pawlik