ImportanceGinkgo diterpene lactone meglumine (GDLM) has attracted much attention because of its potential neuroprotective properties in ischemic stroke. The efficacy of GDLM in patients with acute ischemic stroke (AIS) needs to be verified by well-designed randomized clinical trials.ObjectiveTo assess the efficacy and safety of GDLM in patients with AIS.Design, Setting, and ParticipantsThis multicenter, randomized, double-blind, placebo-controlled, parallel-group trial involved 3448 patients who had AIS, were aged 18 to 80 years, had a clinically diagnosed AIS symptom within 48 hours of onset, had a modified Rankin Scale (mRS) score of 0 or 1 prior to onset, and had a National Institutes of Health Stroke Scale score ranging from 4 to 24. The trial took place at 100 centers in China from February 1, 2016, to May 1, 2018. The mRS is a global stroke disability scale with scores ranging from 0 (no symptoms or completely recovered) to 6 (death). The National Institutes of Health Stroke Scale is a tool used by clinicians to quantify impairment caused by stroke (range, 0-42, with higher scores indicating greater severity). Data were analyzed from January 2019 to December 2022.InterventionsPatients were randomized to receive GDLM or placebo once daily via intravenous infusion in a 1:1 ratio. The treatment was dispensed within 48 hours after symptoms and continued for 14 days. Interventions of thrombolysis and thrombectomy were not permitted during the treatment.Main Outcomes and MeasuresThe primary outcome was the proportion of patients with an mRS of 0 or 1 on day 90 after randomization. Safety outcomes included adverse events and serious adverse events.ResultsA total of 3448 patients were randomized, with 1725 patients assigned to the GDLM group and 1723 patients assigned to the placebo group. The median (IQR) age of the patients was 63 (55-71) years, and 1232 (35.7%) were women. The primary outcome on day 90 occurred in 877 patients (50.8%) in the GDLM group, and 759 patients (44.1%) in the placebo group (risk difference, 6.79%; 95% CI, 3.46%-10.10%; odds ratio, 1.31; 95% CI, 1.15-1.50; relative risk, 1.15; 95% CI, 1.08-1.24; P < .001). Adverse events occurred relatively equally between the 2 groups (303 [17.6%] vs 298 [17.3%]; risk difference, 0.27%; 95% CI, −2.26% to 2.80%; odds ratio, 1.02; 95% CI, 0.85-1.21; relative risk, 1.02; 95% CI, 0.88-1.17; P = .83).Conclusions and RelevanceAmong patients with AIS in this randomized clinical trial, GDLM improved the proportion of patients achieving favorable clinical outcomes at 90 days compared with placebo.Trial RegistrationClinicalTrials.gov Identifier: NCT02526225