The purpose of antithrombotic therapy is not to recanalyze obstruction but to prevent propagation of thrombus and reocclusion by rethrombosis in the brain arteries. There is no evidence of heparin or heparinoid to improve long-term outcome, although anticoagulant therapy might be indicated for stroke associated with coagulation activation such as progressing stroke, basilar artery thrombosis, cardioembolic stroke at high risk, coagulopathy, and arterial dissection. In patients with nonvalvular atrial fibrillation, there is no evidence of immediate anticoagulation with heparin to improve long-term outcome, which is rather contraindicated for large hemispheric stroke, and it is recommended to start warfarin directly in the safety issue. Aspirin is recommended in the guidelines of many countries, although the efficacy is modest. A clinical trial of the GP IIb/IIIa inhibitor abciximab, which is a more potent antiplatelet agent than aspirin, had recently been conducted, although it was stopped because of the concern on the safety. Clinical trials of dual antiplatelet therapy with aspirin and another antiplatelet agent are ongoing to compare efficacy and safety with aspirin monotherapy in Japan and overseas.