Aim To investigate the role of atherosclerosis in transient ischemic attack (TIA). Methods The comparative study was applied by CDFI between 32 cases of TIA and 24 cases without history of TIA and stroke. In both groups, the stenosis extent of carotid artery, the site with the plaque, the conditions of the plaque surface and the echo inside it were evaluated. Results There was no significant difference between the TIA and the control groups (p>0.05), when the stenosis extent of carotid artery was less than 49%. But when that was more than 50%, there was significant difference between the two groups (p>0.05). The risk for TIA was as 4.3 times as that of control group (Or=4.3, the creditable range: 1.34～13.89). The percentage of the weak echo inside the plaque in TIA and control group were 49.8%±16.4% and 23.6%±8.4%, respectively. Conclusion The carotid atherosclerosis is an important risk factor of TIA, and the stenosis extent of carotid artery and the plaque with weak echo inside are closely related with TIA.