Background The drug coated balloon is a promising endovascular therapy for intracranial atherosclerosis (ICAS), potentially combining the advantages of primary angioplasty and antiproliferative drugs. Previous studies have focused on the paclitaxel coated balloon, revealing promising outcomes in the treatment of ICAS, while concerns about the neurotoxicity of paclitaxel were reported. Sirolimus was shown to have less neurotoxicity in the canine cerebral vasculature. The feasibility and safety of a sirolimus coated balloon (SCB) for ICAS have never been evaluated in humans. We assessed the first-in-human feasibility and safety of SCBs for treating symptomatic patients with severe ICAS.Methods This prospective, open label, single arm cohort study was designed to enroll patients with transient ischemic attacks or non-disabling, non-perforator territory ischemic stroke caused by severe ICAS (70-99%) and following at least 3 weeks after the onset of ischemic symptoms. The primary outcome was stroke or death within 30 days. All patients were followed up to detect restenosis at 6 months.Results A total of 60 eligible patients were enrolled with an average age of 59.4 +/- 10.8 years. The technical success rate of SCBs for ICAS was 100%. Seven patients (11.7%) required stenting because of flow limited dissections or elastic retraction. Three patients (5.0%) had 30 day strokes, including two ischemic strokes and one hemorrhagic stroke. An additional three patients had recurrent stroke or death during follow-up. Ten patients had restenosis but only two had symptoms.Conclusions SCBs may be feasible and safe in selected patients with symptomatic ICAS, with high grade stenosis (70-99%). Further studies are warranted.