Abstract: Objective To explore the relationship between Toll-like receptor 4（ TLR4） in peripheral blood mononuclear cell,cytokine level and carotid atherosclerosis in persons with type A behavior pattern（ TABP）. Methods According to the results of carotid artery ultrasound examination,the subjects were divided into carotid atherosclerosis group（ n = 275）and non-carotid atherosclerosis group（ control group,n = 301）. TABP was defined as score of Minnesota multiphase personality inventory（ MMPI） 2 A subscale greater than or equal to 11 points. TLR4 protein was measured by flow cytometry,and the levels of interleulin（ IL） 6 and IL-18,epinephrine（ E） and norepinephrine（ NE） were measured by enzymelinked immunosorbnent assay（ ELISA）. Results The propotion of TABP in subjects with carotid atherosclerosis was higher than that in control group（ 58. 68% vs 24. 64%,P ＜ 0. 01）. The expression of TLR4 protein in peripheral blood mononuclear cell,IL-6 and IL-18,E and NE levels in serum were significantly higher in carotid atherosclerosis subjects than in control group （ 14. 07 ± 3. 54） % vs（ 9. 81 ± 3. 42） %,（ 301. 87 ± 18. 43） vs（ 274. 44 ± 13. 79） ng / L,（ 450. 39± 28. 66） vs（ 364. 28 ± 34. 78） ng / L,（ 17. 53 ± 9. 98） vs（ 6. 83 ± 5. 16） μg / L,（ 863. 62 ± 240. 58） vs（ 441. 17 ±194. 05） ng / L,all P ＜ 0. 05. Both in subjects with and without carotid atherosclerosis,those with TABP had significantly higher expression of TLR4 protein in peripheral blood mononuclear cell,and higher serum IL-6,IL-18,E and NE levels than non-TABP subjects. Multivariate Logistic regression analysis showed that male,age,hypertension,history of cardiovascular disease,TABP,scores of hostility dimension,the expression of TLR4 protein,IL-6 and IL-18 in peripheral blood mononuclear cell were influential factors for carotid atherosclerosis. Conclusion Sympathetic nervous system（ SNS） in carotid atherosclerosis subjects was more highly activated than in healthy volunteers. SNS was more highly activated in the persons with typical TABP than non-TABP.There was a positive relation between carotid atherosclerosis and expression of TLR4 protein and cytokine in peripheral blood mononuclear cell in subjects with TABP.