A faultless endothelial layer is decisive for vascular function and therewith graft's patency. Functional impairment of the endothelium increases risk of graft thrombosis, intimal hyperplasia, and consecutive accelerated graft atherosclerosis. Storage solutions for intra-operatively harvested saphenous vein segments (SVS) might have significant impact on endothelial function. We investigated the impact of short-time storage in physiological saline solution (PSS) and a potassium-chloride- and N-acetylhistidine-enriched storage solution on venous endothelial function. Methods: Intra-operatively isolated SVSs (n=19) were stored in different storage solutions for 90min. They were then immediately studied in tissue bath at 36°C with continuous oxygen insufflation. Following preconstriction with norepinephrine, dose-response relaxation curves of bradykinine (Brad) and sodium nitroprusside (SNP) were determined. We compared developed maximum wall tension, vessel constriction kinetics, endothelial cell- and smooth muscle cell (SMC)-dependent vasodilatory function. Results: Maximum vessel wall tension was reduced significantly in PSS-stored vessels (10.1±9.8mNmm ^-1 vs 3.5±3.4mNmm ^-1; p=0.0372). Endothelium-derived vasodilatory function was likewise significantly reduced after short-time storage (20.6±34.4% vs 35.0±27.0%; p=0.0437). SNP-mediated SMC-vasodilatory function was maintained equally well in both groups (88.2±21.8% vs 83.0±30.6% in PSS; p=n.s.). Conclusion: Even short-time storage in PSS significantly impairs endothelial vascular function. Concerning the essential role of a faultless endothelial layer, the quite common use of PSS as a storage solution for SVSs in CABG surgery has to be discussed critically.