Objective To assess the effect and safety of Hydroxysafflor Yellow A for Injection (HSYAI) in treating patients with acute ischemic stroke (AIS) and blood stasis syndrome (BSS). Methods A multicenter, randomized, double-blind, multiple-dose, active-controlled phase II trial was conducted at 9 centers in China from July 2013 to September 2015. Patients with moderate or severe AIS and BSS were randomly assigned to low-, medium-, high-dose HSYAI groups (25, 50 and 70 mg/d HSYAI by intravenous infusion, respectively), and a control group (Dengzhan Xixin Injection (& x706f;& x76cf;(sic)& x8f9b;(sic...