Objective To investigate the efficacy and risk factors of carotid artery stenting ( CAS) in patients with uni-lateral and bilateral carotid stenosis .Methods We retrospectively studied 312 cases of patients with CAS diagnosed in xinqiao Hospital between January 2005 and January 2011 .According to the carotid artery lesions , patients were divided in-to the unilateral carotid stenosis group .Periprocedural data and those after one-month follow-up and one-year follow-up were collected in two groups and analysed by statistics .Results A total of 312 patients were enrolled in this study , including 136 patients with bilateral lesions and 176 patients with unilateral lesion .303 of these patients were followed up after one month, and 224 cases after one year.All the 312 patients were implanted with 391 stents.The two groups of patients with transient ischemic attack ( TIA) were different in the incidence of perioperative TIA (1.2%for bilateral lesions and 7.6%for unilateral lesions;P<0.01).Compared with bilateral carotid lesions group , the incidence of early postoperative adverse events (death, stroke, perioperative TIA,and perioperative myocardial infarction ) in unilateral carotid lesion group was lower (5.2%vs 11.4%), but of no statistical significance (P>0.05).The incidence of medium-term adverse events (death, stroke, perioperative TIA, perioperative myocardial infarction, and restenosis) in the bilateral carotid lesions group was significantly higher than in the unilateral group (21.8%vs 9.7%, P<0.01), mainly driven by a higher inci-dence of death, periprocedural TIA, and restenosis (P<0.05).Multivariate analysis showed that left ventricular dysfunc-tion, masculinity , bilateral carotid artery disease , renal insufficiency , and cerebral ischemic symptoms within the last 6 months before intervention , and low-density lipoprotein cholesterol ( LDL-C ) levels were the independent risk factors for medium-term adverse events .Conclusion Patients with bilateral carotid artery disease treated by CAS are more prone to adverse events than those with unilateral disease .