Specific properties of the vessel wall of arteries employed as coronary bypass grafts are thought to play an important role in the short- and long-term performance of these conduits. Heterogeneity in the endothelial and smooth muscle cell function between different arteries may provide particular vessels with properties which will favor them for use as bypass conduits. The aim of this review is to provide an insight into how the vascular reactivity of presently used arterial conduits varies and to discuss the clinical implications of these findings both in terms of flow modulation in response to physiologic and exogenous vasoactive mediators and long-term patency.