Acute ischemic stroke is a major public health burden and globally a common cause of death and disability. Intravenous recombinant tissue plasminogen activator (rt-PA) is approved for use in selected patients with ischemic stroke within 3 hours of symptom onset. The International Stroke Trial or IST-3 seeks to determine whether a wider range of patients may benefit the International Journal of Stroke spoke to chief investigator Dr Peter Sandercock.