Over the past ten years, a body of evidence has accumulated to suggest that aspects of oral health, particularly the extent and severity of periodontal disease, may be associated with an increased risk of coronary heart disease (CHD). This evidence should be seen against the background of a more general interest in the role of chronic infections in vascular disease. There have, for example, been suggestions of associations between CHD and a range of bacterial and viral agents, including H. pylori, C. pneumoniae, and cytomegalovirus, which are involved in persistent infections at various sites around the body. Reviews of the evidence for the causality of these relationships between CHD and specific organisms have been inconclusive. By comparison, periodontal disease is related to a wide and complex range of organisms rather than a single species and although the nature of the relationship is still inconclusive, the evidence for its validity still persists to some degree. A brief synopsis of the epidemiological studies to date and their outcomes is shown in Table 1.