Vasoconstriction of collateral vessels has been previously reported as a mechanism of spontaneous transient ischemic episodes and after the administration of ergonovine. This case report describes a 47-year-old woman with mixed angina and a right coronary artery occlusion supplied by a collateral system related to the left anterior descending artery. Angina and ECG changes at rest were present for more than 1 year and also provoked by intracoronary ergonovine which induced collateral vasoconstriction. To the best of our knowledge, this report is the first demonstration that the reopening of the right coronary artery and the disappearance of collateral vessels may definitively relieve angina and ECG changes occurring at rest, thus confirming small coronary vessel constriction as the main cause of the disease status.