Twelve patients 8 females and 4 males, whose ages varied from 33 to 60 years (median 50.6 years), were seen at the Hospital for Cardiology and Neurology of the Mexican Institute for Social Security. All were diagnosed as having angor pectoris, through the clinical history and physical exam. Three patients had stable angor and in nine it was of an unstable type. The resting ECG showed signs of subepicardial ischemia in five cases. In eight the stress ECG according to the Bruce technic showed depression of the ST segment over 1 mm. In one patient atrial stimulation was performed with a pacemaker and ischemic changes of the ST segment were normal in all cases; in two however, coronary spasm that reversed with nitroglycerin appeared. The left ventriculogram was normal in all but one that revealed diaphragmatic hypokinesia associated with right coronary spasm. All patients were followed from two to fifty six months (median 19.4), and only in one case the angor pectoris remained unchanged. In all others it decreased or disappeared. During this time there were no deaths, myocardial infarctions or severe arrhythmias.