Droprenilamine hydrochloride is coronary vasodilator. It is a secondary amine structurally related to the antianginal drug prenylamine. It increases coronary flow in the isolated guinea-pig heart and partially inhibits pitressin-induced ST-segment changes in anaesthetized rats. Droprenilamine hydrochloride also elevated coronary blood flow in the anaesthetized greyhound and reduced the incidence of cardiac dysrhythmias, which result from acute ligation of the anterior descending branch of the left coronary artery. Droprenilamine hydrochloride only reduced heart rate when administered after coronary artery occlusion, a fact, which may be related to the effects of the drug on the increased sympatho-adrenal outflow produced by myocardial ischemia.