BackgroundDanhong injection (DHI) has been widely prescribed to patients with acute ischemic stroke (AIS). However, due to methodological deficiencies, previous research has not yet provided rigorous evidence to support the use of DHI in the treatment of AIS. Therefore, we designed this multicenter, randomized, controlled, and double-blind trial to evaluate the efficacy and safety of DHI for AIS.Methods/DesignIt is a randomized, multicenter, double-blind, placebo-controlled, adaptive clinical trial. A total of 864 eligible patients will be randomized into either the DHI or placebo group in a 2:1 ratio. All patients will be given the standard medical care as recommended by guidelines. Participants will undergo a 2-week treatment regimen and 76-day follow-up period. The primary outcome is the proportion of patients with a favorable outcome, defined as a score of 0–1 on the modified Rankin scale at day 90. Secondary outcomes include a change in the total score of the Chinese medicine symptom scales of “Xueyu Zheng” (blood stasis syndrome), the proportion of patients with a Barthel Index score of ≥90, the proportion of patients with an improvement in NIHSS score of ≥4 or NIHSS score of 0–1, quality of life measured by the EQ-5D scale, etc. Safety outcomes such as global disability (mRS ≥3) at day 90 will also be assessed. The changes in mRNA and microRNA profiles in 96 patients selected from certain centers will also be assessed. As this is an adaptive design, two interim analyses are prospectively planned, which will be carried out after one-third and two-thirds of patients have completed the trial, respectively. Based on the results of the interim analyses, the Data Monitoring Committee (DMC) will decide how to modify the study.DiscussionThis trial will provide high-quality evidence for DHI in treatment of AIS.Trial registrationClinical Trials.gov NCT01677208 (Date of registration 22 December 2012).Electronic supplementary materialThe online version of this article (doi:10.1186/s13063-015-1076-4) contains supplementary material, which is available to authorized users.