A large body of evidence links antagonism-related traits with cardiovascular outcomes, but less is known about how psychological traits are associated with intermediate markers of cardiovascular disease. Using a large, community-based sample from Sardinia, Italy (n=5614), this study examined how trait antagonism (low agreeableness) and its facets are associated with carotid artery intima-media thickness, a measure of arterial thickening. Controlling for demographic and cardiovascular risk factors, low agreeableness and, in particular, low straightforwardness and low compliance, were associated with greater carotid thickening, measured concurrently and prospectively, and with increases in intima-media thickness over 3 years. Indeed, those in the bottom 10% of agreeableness had a 40% increase in risk for elevated intima-media thickness. Although men have thicker arterial walls, women with antagonistic traits had similar carotid thickening as antagonistic men. Antagonistic individuals, especially those who are manipulative and aggressive, have greater increases in arterial thickening, independent of traditional cardiovascular risk factors.