AIMS: We investigated the relationship between autonomic nervous system balance, systemic immune activation, endothelial dysfunction, and depression in patients free of coronary heart disease (CHD) with increased CHD risk. METHODS AND RESULTS: Depression status (Beck Depression Inventory, BDI), selected CHD risk factors, inflammation markers, measures of heart rate variability (HRV), and indices of endothelial function (flow-mediated dilation, FMD) were evaluated in 415 subjects free of CHD, diabetes mellitus, and other life-threatening conditions, with at least two CHD risk factors among the following: older age, male gender, current smoking, hypertension, and dislipidaemia. Overall, 51.7% of the participants were males, aged 57.6 +/- 8.8 years on average (minimum 30, maximum 70). Almost half were hypertensive, 43.9% were dyslipidemic, 30.4% current smokers, and 23.1% showed a depressive symptomatology (BDI > or = 10). Logistic regression showed that, as compared with non-depressed individuals and after adjustment for age, gender, and hypertension, depressive subjects were significantly more likely to be smokers, to have higher total cholesterol, higher C-reactive protein, and Interleukin-6. In addition, depressed subjects were more likely to have altered HRV and their FMD was severely impaired (adjusted odds ratio of 1% increase = 0.72; 95% CI: 0.61-0.86). CONCLUSION: Our data indicate an independent association between depression and impaired HRV, systemic inflammatory, and endothelial function. These mechanisms play a role not only in the complication of advanced forms of disease, but also promote and/or accelerate the early disease and connect depression and CHD.