Abstract—The aim of this study was to evaluate the influence of traditional and nontraditional (oxidation markers) cardiovascular risk factors on the degree of adaptive response of the carotid wall to atherosclerotic disease, a process known as arterial enlargement. Five thousand sixty-two clinically healthy, middle-aged women living in the area of Naples participated in the "Progetto Atena" study; 310 of these women (potentially at higher atherosclerotic risk) underwent a high-resolution ultrasound scan of the carotid arteries. In addition to routine biochemical tests, these women had the determination of serum IgG antibody titer against oxidized LDL and measurement of thiobarbituric acid reactive substances and total radical-trapping activity potential of plasma. Age, systolic blood pressure, body mass index, and radical-trapping activity were all positively correlated with external and internal common carotid diameters, whereas triglycerides (positively) and HDL cholesterol (inversely) were related only to external diameter. After controlling for traditional cardiovascular risk factors, associations still persisted for age, systolic blood pressure, and plasma radical-trapping activity with external carotid diameters. However, in the quartile of women with highest total cholesterol (>7.38 mmol/L), the slope of the regression line between systolic blood pressure and external diameter was significantly flatter than in the three other quartiles (test for difference, P=0.014). Outward carotid enlargement is related to traditional and nontraditional risk factors and comes even before plaque development. Women with poor resistance to oxidative stress potentially have a difficulty to remodel their arteries in response to atherosclerotic stimuli.