Background Whether the safety and efficacy of percutaneous transluminal angioplasty and stenting (PTAS) is significantly different from that of medical treatment alone for symptomatic intracranial arterial stenosis (ICAS) is debatable. A study was undertaken to determine the safety and e & iuml;<not sign><euro>icacy of both treatments for symptomatic ICAS. Methods This preplanned pooled individual patient data analysis included 400 participants treated with PTAS and 409 treated with medical treatment alone in two large multicenter randomized clinical trials (SAMMPRIS and CASSISS). Patients were treated with PTAS using a self-expanding stent or medical treatment alone. The primary outcome was stroke or death within 30 days, or ischemic stroke in the territory of the qualifying artery more than 30 days after enrollment. Results Individual data were obtained for 809 patients, 451 from SAMMPRIS and 358 from CASSISS. 400 participants were randomly assigned to the PTAS group and 409 to the medical group. The risk of the primary outcome was not significant between the PTAS and medical groups (17.5% vs 13.2%; HR 1.37 (95%& acirc;<euro>parts per thousand CI 0.96 to 1.95), P=0.08). However, the risk of stroke or death within 30 days was higher in the PTAS group (10.5% vs 4.2%; HR 2.62 (95%& acirc;<euro>parts per thousand CI 1.49 to 4.61), P<0.001). Patients of white ethnicity (HR 1.97, 95% CI 1.17 to 3.31) and those with hyperlipidemia (HR 2.04, 95% CI 1.27 to 3.26) or a transient ischemic attack (TIA) (HR 2.19, 95% CI 1.08 to 4.45) were at higher risk for PTAS. Conclusions PTAS poses an increased risk of short-term stroke/death and therefore is not advised as primary treatment for symptomatic ICAS. A balance exists between stroke risks and revascularization benefits. For patients with asymptomatic ICAS of white ethnicity and those with hyperlipidemia or a history of TIA, a thorough assessment is warranted before considering PTAS.