Red blood cell distribution width (RDW) is related to morbidity and mortality in a wide spectrum of conditions, including atherosclerotic processes. In the present study, we aimed to investigate the significance of RDW in saphenous vein graft disease (SVGD), in which atherosclerosis plays an important pathophysiological role.In all, 90 patients were enrolled in the study, 58 with patent SVGs and 32 with SVGD. Stable angina and/or positive stress tests were indications for coronary angiography. RDW and other laboratory parameters were measured before coronary angiography.Baseline characteristics of the patient groups were similar. Although triglyceride levels of the SVGD group were higher than those of the patent SVG group, the difference did not reach statistical significance (188.9 ± 99.8 mg/dL vs 151.0 ± 75.5 mg/dL, respectively; P = 0.068). Mean time interval after bypass surgery was longer in the SVGD group compared with the patent SVG group (7.8 ± 4.5 years vs 5.6 ± 3.1 years, respectively; P = 0.008). The RDW values of patients with SVGD were higher than those of patients in the patent SVG group. In logistic regression analysis, RDW and time since bypass graft were retained as independent predictors for SVGD.In the present study, we showed for the first time that RDW, which is a simple and inexpensively measured parameter used routinely in daily clinical practice, can be used as a predictor of SVGD, together with time since bypass surgery.