We report an unusual case of vasospasm of a grafted radial artery complicated with ventricular fibrillation during the postoperative course of coronary artery bypass graft surgery. To our knowledge this is the first documented case of a radial artery graft spasm leading to a severe arrhythmia. The arrhythmia resolved spontaneously. Radial artery graft spasm was demonstrated by angiography and was successfully resolved by intravenous nitroglycerin administration.