Aim To investigate effect of cigarette smoking onmorphology and expression of intercellular adhesion molecule-1 (ICAM-1), ICAM-1 mRNA in vascular endothelial cells of rats' brains and to further explore influence of cigarette smoking on atherogenesis. Methods 75 male Wistar rats were randomly subgrouped into long-term massive, short-term massive, long-term trifle, anti-smoking and normal control group. Immunohistochemistry technique, in situ hybridization technique and pathologic image analyzing system were used to determine the expression of ICAM-1, ICAM-1 mRNA in rats' cerebral vascular endothelial cells. Results In contrast to normal control group, expression of ICAM-1, ICAM-1 mRNA in rats' cerebral vascular endothelial cells increased in smoking (103.7±3.9 vs 99.7±7.1 vs 92.6±5.2 vs 94.8±5.1 vs 84.2±4.7 for the mean gray value of ICAM-1mRNA staining in normal control, anti-smoking, short-term massive, long-term trifle, long-term massive group, repectively; p<0.05), and ICAM-1, ICAM-1 mRNA were relevant to the duration and dose of smoking (p<0.05). Expression of ICAM-1 and ICAM-1 mRNA decreased after anti-smoking, and there was no significant difference compared with normal control group (p>0.05). The structure of endothelial cells changed greatly in smoking, and partly recovered after anti-smoking. Conclusion The upregulation of expression of ICAM-1 and ICAM-1 mRNA might be one of the important molecular mechanisms during the process of atherosclerosis in cigarette smoking rats.