Wu et al1 have shown that periodontal disease is another putative and independent risk factor for cerebrovascular disease, particularly for ischemic stroke. Presently, it is unknown whether the association between periodontal disease and stroke is causal. Several pathogenic pathways make a causal linkage possible. Beck at al2 hypothesized that subjects with genetically determined strong monocytic response to bacterial antigens could be at high risk for developing both periodontal disease and atherosclerosis. It is also possible that a susceptibility to strong inflammatory response could increase the risk of both periodontitis and stroke. Inflammation in the vessel wall plays an essential role not only in the initiation and progression of atherosclerosis but also in the erosion or fissuration of plaques and eventually in the rupture of plaques.3