Objective:To study the association between cigarette smoking and the severity of coronary atherosclerosis. Methods:The study population consisted of 1060 consecutive patient who underwent coronary angiography for suspected or known coronary atherosclerosis. The severity of coronary atherosclerosis was defined by Gensini’s score .The Spearman two-way test and partial correlation analysis was used to assess the relation between two quantitative variables. The independent-sample T test was employed to investigate the distribution of the clinical data in two groups according to smoking status. Multivariate stepwise linear regression analysis was employed to explore the independent relationship between smoking and the severity of coronary atherosclerosis. Results:Spearman’s correlation analysis indicated that smoking was positively correlated with leukocyte count, neutrophil, CH/HDL-C, LDL-C/HDL-C and the Gensini’s score. Leukocyte count, neutrophil, CH/HDL-C and LDL-C/HDL-C was positively correlated with the Gensini＇s score, and partial correlation analysis showed that smoking was still positively correlated with the Gensini’s score while the age and the sex were under controlled. Independent-sample T test also found the significant differences in terms of leukocyte count, neutrophil, CH/HDL-C and LDL-C/HDL-C between the smoking group and non-smoking group. Multiple stepwise linear regression analysis demonstrated that neutrophil, smoking index and LDL-C/HDL-C significantly independently associated with Gensine’s score. Conclusion:Smoking was independently associated with the severity of coronary atherosclerosis, as measured by Gensini＇s score. Inflammatory response and hyperlipidemia may be the mechanism involved.