Background: The relation of depressive mood to coronary endothelial dysfunction is not documented. We investigated whether depressive symptomatology was associated with coronary endothelial dysfunction in patients without coronary artery disease (CAD). Methods: In 160 patients without overt CAD and any medications, incremental acetylcholine (Ach; 20 µg, 50 µg and 100 µg/min) and nitrate (NTG; 200 µg/min) were infused into the left coronary ostium. All patients were divided into two groups, depressive group (n=54, male 30, 51.8 yrs), as indicated by a Beck Depression Inventory (BDI) score ��� 10 and a Hamilton Depression Rating Scale (HAM-D17) ��� 7, and non-depressive group (n=96, male 64, 51.3 yrs). The vascular response to each drug was quantitatively measured at the same site of left anterior descending artery. Results: Patients in depressive group showed a significant vasoconstriction compared with patients in non-depressive group (p=0.017, 0.090, 0.004, respectively, Figure). Endothelium-independent vasodilatation to nitrates did not differ significantly between two groups (p=0.461, Figure). There were no differences of risk factors between two groups. Conclusions: Depressive mood is associated with coronary endothelial dysfunction in patients without CAD, suggesting a possible mechanism by which depressive mood may act as a cardiovascular risk factor.