Background: Anti-inflammatory therapy using colchicine has reduced recurrent vascular events in patients with coronary heart disease. Design: Colchicine in High-risk Patients with Acute Minor-to-moderate Ischemic Stroke or Transient Ischemic Attack (CHANCE-3) is a randomized, double-blind, placebo-controlled multicenter trial, in which 8,238 patients with acute minor-to-moderate ischemic stroke (NIHSS ⩽ 5) or high-risk transient ischemic attack (TIA) (ABCD² score ⩾4) and a high-sensitivity CRP (hsCRP) level of ⩾2 mg/L will be randomly assigned within 24 h of symptom onset to colchicine (1 mg daily on days 1–3, followed by 0.5 mg daily for a total of 90 days) or matching placebo, on a background of optimal medical therapy. The study will have 90% power to detect a 25% reduction in the primary efficacy outcome of any stroke within 3 months of randomization. Adverse events potentially related to the use of colchicine will also be analyzed. The primary analysis will be by intention to treat. Trial registry name: Colchicine in High-risk Patients with Acute Minor-to-moderate Ischemic Stroke or Transient Ischemic Attack (CHANCE-3); URL: https://clinicaltrials.gov/ct2/show/NCT05439356?cond=CHANCE-3&draw=2&rank=1 ; Registration number: NCT05439356.