A 59-year-old white man underwent multiple coronary artery bypass grafts (CABGs) on an emergency basis for severe stenosis of the left main, and occlusion of the right coronary, artery. One month after operation recurrence of angina prompted a new diagnostic evaluation. Occlusion of the grafts was detected at angiography. Accurate hematological screening before reoperation showed decreased levels of protein S. One year after his second operation, the patient is asymptomatic on oral anticoagulant therapy. Tallium-201 scintigraphy shows normal myocardial perfusion.