An association between dental and other bacterial infections and coronary heart disease has recently been observed in both cross-sectional and longitudinal studies. To elucidate this topic, the severity of dental infections and coronary atheromatosis was assessed, together with measurements of the conventional coronary risk factors, in 100 individuals (88 men, 12 women, mean age 48, range 28-68 years) referred for diagnostic coronary angiography. Pantomography X-rays and coronary angiograms of the participants were scored blindly by single observers, a dentist and a radiologist respectively. The median pantomography score was 3.0 in male individuals belonging to the highest tertile of coronary atheromatosis score, as compared with 0.0 among the rest of the male participants (P = 0.003). The association between dental infections and severe coronary atheromatosis in males remained significant after adjusting for the effect of age, blood lipids, body mass index, hypertension, smoking and social class. No association between dental infections and coronary atheromatosis was observed in the small number of females studied. This observation supports the proposal that bacterial infections play a role in the pathogenesis of coronary atherosclerosis.