At present, the value of endothelial function as a prognostic tool has been evaluated only in selected groups of patients with mild or minor coronary artery disease, not in the complete spectrum of patients presenting with angina. The objective of this study was to evaluate whether endothelium-dependent vasodilation of the coronary arteries in response to acetylcholine infusion as a marker of endothelial function would have prognostic value in patients referred for a first coronary angiogram. The data suggest that endothelial function assessment does not contribute to the prediction of outcomes in patients referred for a first coronary angiogram.