Type II diabetes mellitus (DM) and the metabolic syndrome, both characterized by insulin-resistance, are associated with an accelerated form of atherosclerotic vascular disease and poor outcomes following vascular interventions. These vascular effects are thought to stem from a heightened inflammatory environment and reduced bioavailability of nitric oxide. To better understand this process, we characterized the vascular injury response in the obese Zucker rat by examining the expression of adhesion molecules, the recruitment of inflammatory cells, and the development of intimal hyperplasia. We also evaluated the ability of exogenous NO to inhibit the sequela of vascular injury in the metabolic syndrome. Obese and lean Zucker rats underwent carotid artery balloon injury. ICAM-1 and P-selectin expression were increased following injury in the obese animals as compared to the lean rats. The obese rats also responded with increased macrophage infiltration of the vascular wall as well as increased neointima formation compared to their lean counterparts (I/M = 0.91 vs 0.52, P=0.001). Following adenovirus-mediated iNOS gene transfer, ICAM-1, P-selectin, inflammatory cell influx, and oxidized LDL receptor expression were all markedly reduced versus injury alone. iNOS gene transfer also significantly inhibited proliferative activity (54% and 73%; P<0.05) and neointima formation (53% and 67%; P<0.05) in lean and obese animals, respectively. The vascular injury response in the face of obesity and the metabolic syndrome is associated with increased adhesion molecule expression, inflammatory cell infiltration, oxidized LDL receptor expression and proliferation. iNOS gene transfer is able to effectively inhibit this heightened injury response and reduce neointima formation in this pro-inflammatory environment.