Abstract—The RhoA/Rho kinase (ROCK) pathway is a new mechanism of remodeling and vasoconstriction. Few data are available regarding ROCK activation when angiotensin I–converting enzyme is high and blood pressure is normal. We hypothesized that ROCK is activated in the vascular wall in normotensive rats with genetically high angiotensin I–converting enzyme levels, and it causes increased vascular expression of genes promoting vascular remodeling and also oxidative stress. Aortic ROCK activation, mRNA and protein levels (of monocyte chemoattractant protein-1, transforming growth factor [TGF]-₁, and plasminogen activator inhibitor-1 [PAI-1]), NADPH oxidase activity, and O₂^·- production were measured in normotensive rats with genetically high (Brown Norway [BN]) and low (Lewis) angiotensin-I–converting enzyme levels and in BN rats treated with the ROCK antagonist fasudil (100 mg/kg per day) for 7 days. ROCK activation was 12-fold higher in BN versus Lewis rats (P<0.05) and was reduced with fasudil by 100% (P<0.05). Aortic TGF-1, PAI-1, and monocyte chemoattractant protein-1 mRNA levels were higher in BN versus Lewis rats by 300%, 180%, and 1000%, respectively (P<0.05). Aortic TGF-1, PAI-1, and monocyte chemoattractant protein-1 protein levels were higher in BN versus Lewis rats (P<0,05). Fasudil reduced TGF-1 and PAI-1 mRNA and TGF-1, PAI-1, and monocyte chemoattractant protein-1 protein aortic levels to those observed in Lewis rats. Aortic reduced nicotinamide-adenine dinucleotide phosphate oxidase activity and ·O₂^- production were increased by 88% and 300%, respectively, in BN rats (P<0.05) and normalized by fasudil. In conclusion, ROCK is significantly activated in the aortic wall in normotensive rats with genetically high angiotensin-I–converting enzyme and angiotensin II, and it causes activation of genes that promote vascular remodeling and also increases vascular oxidative stress.