Background. Saphenous vein graft disease (SVGD) after by-pass surgery is an important cause of morbidity and mortality for patients with coronary artery disease. Comprehensive evaluation of biochemical and hematological parameters associated with this problem is limited. Plateletcrit (PCT) provides complete information on total platelet mass, but it has not been previously studied. In this study, we examined the relationship between SVGD and platelet parameters such as PCT, mean platelet volume, platelet count, and platelet distribution.