Sirolimus-eluting stents (SES) prevent neointimal proliferation and have been widely used to treat stenotic lesions in coronary arteries because of a significant reduction of restenosis in comparison with bare-metal stents. Sirolimus, however, may cause endothelial dysfunction by damage to vascular endothelium or impairing vascular repair. Recent studies report the occurrence of exercise- or acetylcholine-induced coronary vasoconstriction in the vessel segments adjacent to the SES. We report here a clinical case of intractable Prinzmetal's angina 3 months after SES implantation and recommend extended, thorough follow up of patients who have undergone SES implantation.