Endothelium plays a key role in maintenance of vascular homeostasis. Cardiovascular risk factors promote development of endothelial dysfunction, characterized by increased vasoconstriction and by procoagulant/pro-inflammatory endothelial activities. In coronary artery, endothelium-dependent dilation improves blood flow, while the occurrence of endothelial dysfunction reduces myocardial perfusion, so new methods have been developed for assessment of endothelial function in coronary and peripheral arteries. The quantitative angiography with intracoronary infusion of acetylcholine remains the "gold standard" to assess the endothelium-dependent vasodilatation. The use of this technique is restricted to patients who have a clinical indication for coronary angiography, so new imaging methods have been considered for noninvasive diagnosis of coronary microvascular disease, such as magnetic resonance imaging phase contrast and positron emission tomography. The advent of new techniques has facilitated testing of endothelial dysfunction in peripheral arteries with non-invasive methods. This review presents available in-vivo and ex-vivo methods for evaluating endothelial function with special focus on more recent ones. The diagnostic tools include local vasodilatation by venous occlusion plethysmography and assessment of flow-mediated dilatation, arterial pulse wave analysis and pulse amplitude tonometry, laser Doppler flowmetry. The possibility to detect endothelial dysfunction as an early marker of atherosclerosis makes these instruments useful for early stratification of patients at risk for cardiovascular events. Aim of this review is to summarize the characteristics of non-invasive assessment of endothelial function in order to optimize cardiovascular risk management.