Cigarette smoking, an established cardiovascular (CV) disease risk factor, is known to adversely influence atherosclerosis and its relationship to other risk factors in middle-aged and older adults. However, information is limited in this regard in younger adults. This aspect was examined in a sample of 697 cigarette smokers and 311 nonsmokers, aged 25-44 years, from a biracial (black-white) community. Carotid intima-media thickness (IMT), a surrogate measure of coronary atherosclerosis, was measured by B-mode ultrasonography to obtain the mean value of far wall readings of carotid artery segments (common, bulb, internal) on both sides. Smokers vs nonsmokers showed lower levels of body mass index (27.1 vs 29.5 kg/m2, p < .001), insulin (10.2 vs 13.2 μU/mL, p = .001), glucose (80.9 vs 83.3 mg/dL, p < .001), and HDL cholesterol (46.8 vs 48.4 mg/dL, p < .001), but higher levels of systolic blood pressure (117.8 vs 115.5 mm Hg, p < .001) and carotid IMT (0.845 vs 0.789 mm, p < .001). Further, smoking significantly accelerated the deleterious effects on carotid IMT by age (0.016 vs 0.008 mm IMT increase/year, p = .010) and systolic blood pressure (0.004 vs 0.002 mm IMT increase/mm Hg, p = .028). In conclusion, cigarette smoking significantly increases carotid IMT and exacerbates the adverse effects of age and systolic blood pressure on carotid IMT in young adults. The effects on vascular changes by studying carotid IMT underscore the need for aggressive early prevention and intervention strategies to control smoking behavior.