This report describes a 45-year-old Japanese man who had episodes of anginal chest pain on effort. Coronary arteriography in the baseline state revealed subtotal occlusion in the mid-portion of the left anterior descending coronary artery. After intracoronary infusion of an endothelium-dependent vasodilator, substance P, the subtotal occlusion was immediately abolished. We concluded that endothelium-dependent vasodilation evoked with substance P was present at the site where coronary vasospasm occurred spontaneously in our case.