The cardiovascular tolerance for sex has largely been equated with physical activity, yet sexual arousal plays a major role. Exercise testing is useful, primarily for evaluating functional capacity, which reflects the extent of physical conditioning and the limitation imposed by symptoms of angina, dyspnea, and fatigue. Exercise testing, which is useful for evaluating functional capacity in sedentary patients, is generally unnecessary in physically active patients. Exercise testing, with or without radionuclide imaging, is of limited value in assessing the risk of future cardiovascular events-a limitation shared by all diagnostic tests, including coronary angiography. The absolute risks of coition-induced myocardial infarction (MI) or death are extremely low-on the order of 2 chances per million per hour in healthy middle-aged individuals or 20 chances per million per hour in "high-risk" patients with ischemic heart disease. This is equivalent to an annual risk of 1. 01% and 1.2%, respectively. Sex is a comparatively weak precipitant of acute coronary events, accounting for only 0.5-1.0% of all such events. The cardiovascular tolerance for sex in an individual can be characterized by the "functional reserve," that is, the extent to which the cardiovascular response to sex-measured by the heart rate, blood pressure, and oxygen consumption-encroaches on the peak response to exercise. Cardiovascular symptoms during sex rarely occur in patients who do not experience similar symptoms during exercise testing at a level equivalent to 6 METS.