Although the presence of coronary artery calcium (CAC) has been associated with the prevalence and incidence of coronary heart disease (CHD), it is unclear if this association has a threshold or a continuous relation. The aim of this research was to explore the relation between CAC, as detected by electron beam tomography (EBT), and CHD in a cross-sectional study of women and men who presented to a single center for elective screening with EBT from 1995 to 1998. Of 17,967 participants, patients with CHD had higher CAC levels than those without CHD. Using subjects without CAC as the referent group, the odds ratios for prevalent CHD increased significantly across increasing quartiles of CAC in the overall population and in both genders. In a subset of the population, after adjusting for CHD risk factors, CAC scores in the fourth quartile were associated with an odds ratio of 33.8 (p <0.001) for prevalent CHD. Among patients with and without CHD, men were more likely than women to have detectable CAC (58.1% vs 28.3% and 96.1% vs 68.9% respectively, p <0.001 for each); the prevalence of detectable CAC increased with age and was higher in men than in women. There was an increased risk for prevalent CHD at all levels of CAC >0, with the greatest increase in risk occurring in patients with CAC scores >95. These observations support the potential of EBT as a sensitive test for detection of CHD.