In 12 patients we assessed the effect of inhaled salbutamol on the coronary circulation. According to our results, large doses of salbutamol increase coronary flow, but not in proportion to the needs of the myocardium (as documented by the increase in coronary oxygen extraction), and decrease coronary flow reserve. These effects may have deleterious consequences in patients with coronary artery disease, causing or worsening myocardial ischemia.