The human saphenous vein (SV) suffers trauma during harvesting for CABG which reflects on the graft patency (Souza 1996, Souza et al. 2006, Dashwood and Loesch 2007). Commonly used harvesting procedures involve stripping the pedicle of connective tissue from the vein followed by the distension to overcome venospasm (Souza 1996). Such procedures cause structural damage of the vein vascular smooth muscle cells (VSMC) and rapid expression of immunoreactive iNOS (Loesch et al. 2006). Here, we used standard protocols of immunolabelling for confocal and electron microscopy (EM) and Western blot analysis to study the co-expression of iNOS and ET-1 in medial VSMC of SV harvested in patients undergoing CABG. Following local ethics committee approval and patients’ informed consent, segments of SV harvested for CABG (n=10) were collected during surgery. For EM, SV samples were fixed in 4% paraformaldehyde and 0.1% glutaraldehyde prior to single and double immunolabelling with ExtrAvidin and immuno-gold methods using antibodies to iNOS (polyclonal SC-651, Santa Cruz Biotech) and ET-1 (monoclonal MCE-6901-01, Peninsula Labs). For the confocal microscopy frozen SV sections were labelled with iNOS and ET-1 antibodies in conjunction with Alexa Fluor® 568 and 488 (Molecular Probes), respectively. Both confocal and EM revealed the co-expression of iNOS and ET-1 in VSMC of SV harvested for CABG (Fig. 1A-C and 2A-C). The immunoreactivity was predominantly localised in structurally damaged VSMC (Fig. 2). Western blot analysis showed increased iNOS and ET-1 levels in extracts from stripped and distended SV as compared to SV harvested without stripping and distension (Fig. 2D). Conventional harvesting of SV for CABG induces both iNOS and ET-1 in structurally distorted VSMC. The functional consequences of co-expressed iNOS and ET-1 in venous VSMC require further investigation.