Anticoagulants have been used in patients with acute ischemic stroke to limit infarct volume and to prevent reinfarction and thrombotic complications like deep venous thrombosis. Three important randomized trials of anticoagulants have been reported recently. One trial showed that nadroparin reduced the percentage of patients with poor outcome at 6 months. One unblinded trial of subcutaneous unfractionated heparin showed that heparin reduced the rate of early recurrent stroke, but this benefit was offset by an increase in hemorrhages. A trial of the heparinoid ORG 10172 showed no efficacy overall at 3 months, although there was an increase in patients with very favorable outcomes at 7 days. The defibrinogenating agent ancrod has shown promise in a series of small clinical trials, but efficacy has not been established. There are no reliable data on the use of antithrombotic agents to prevent reocclusion after thrombolytic therapy. Anticoagulants are generally recommended in patients with cerebral venous thrombosis, but the recommendation is supported by only one small and methodologically limited trial.