Recent clinical studies have reported that testosterone therapy reduces myocardial ischaemia in men with coronary artery disease, and the beneficial modulation of coronary vascular tone by testosterone has been proposed as an effector mechanism. Maintenance of a correct response to vasoconstrictive and vasodilatory agents is essential in the control of vascular tone. Endothelial dysfunction, most commonly manifested through an elevation in vascular tone, is implicated as an initiating factor in conditions such as hypertension and atherosclerosis. Increased sensitivity to vasoconstrictive stimuli is also proposed in the development of heart failure and hypertensive vascular remodelling, while increased coronary vascular reactivity to vasoconstrictive factors is likely further to restrict coronary blood flow through the partially occluded atherosclerotic vessel. Reduced vasodilatation and enhanced vasoconstriction can also lead to vasospasm and exacerbation of anginal symptoms. Testosterone is well known to elicit direct vasodilatation, but its influence upon responses induced by other vasoactive agents is less coherent, and may depend upon the underlying pathogenic process or gender. The aim of this review is to present the data obtained from both the patient and animal studies conducted to date, to ascertain any influence testosterone may have upon the regulation of vascular tone.