Objective: To investigate the relations between serum bilirubin and carotid atherosclerosis in patients with hypertension.Patients and Methods: Carotid artery ultrasonography was performed in 198 patients (104 males, average age of 65.6±7.1 years) with hypertension. Serum levels of bilirubin and C-reactive proteins (CRP) were measured at the same time.Results: Carotid atherosclerosis was detected in 133 patients, 87 of them had carotid artery plaque. The prevalence of stroke (20.3%) and myocardial infarction (13.5%) in the atherosclerosis group was higher than in the non-atherosclerosis group (9.2% and 6.2% respectively, P<0.05). The average total serum bilirubin in the atherosclerosis group was lower than in the non-atherosclerosis group (12.8±1.3 vs 16.8±1.5 'mol/L, P<0.01), whereas the average serum of CRP was higher (4.1±1.1 vs 2.3±0.7 mg/L, P<0.01). After adjusting other factors such as age, total cholesterol, diabetes and systolic blood pressure, total serum bilirubin was negatively associated with carotid atherosclerosis in women and men, with odds ratios of 0.49 (95% CI, 0.28 to 0.71; P<0.01) and 0.66 (95% CI, 0.46 to 0.80; P<0.01). Serum CRP was positively correlated to carotid atherosclerosis, with odds ratios of 1.76 (95% CI, 1.36 to 2.04; P<0.01) in women and 1.95 (95% CI, 1.46 to 2.82; P<0.01) in men.Conclusions: Carotid atherosclerosis is associated with a high prevalence of stroke or myocardial infarction in hypertensive patients. Serum bilirubin is negatively associated with the carotid atherosclerosis.