Nitric oxide (NO) is an endothelium-derived relaxing factor which plays a role in atherogenetic events. Polymorphisms in the endothelial NO synthase gene (eNOS) influences the functional activity of the enzyme and affect the susceptibility to atherogenesis. In this study we determined whether T-786C, G894T and 4a/4b eNOS genetic variants may increase the susceptibility to carotid atherosclerosis.