The aim of this study was to investigate if there was a link between the relaxant responses in saphenous vein (SV) and internal mammary artery (IMA) segments obtained from patients undergoing coronary artery bypass grafting and the patients' cardiovascular risk factors. Endothelium-(in)dependent relaxations were assessed by isometric tension studies. Endothelium-dependent relaxant responses were greater in IMA than SV and gender, smoking profile and history of hypertension but not diabetes appeared to have an influence on these responses. Endothelium-dependent relaxant responses in both IMA and SV were greater in males than females and relaxant responses in IMA segments were attenuated in smokers, whereas the opposite effect was noted in SV segments. Endothelium-dependent relaxant responses in SV were lower in patients with hypertension. Endothelium-independent relaxant responses were greater in IMA than SV. Endothelium-independent responses were greater in male patients' SV segments, but gender played no role in IMA segments. Diabetes had no effect on endothelium-independent responses in IMA, but SV segments from diabetic patients had greater responses. Neither conduit's endothelium-independent response was affected by hypertensive status. The relationship between risk factor status and endothelial responses is multifactorial, with gender, hypertension, diabetes and smoking status all contributing.