The purpose of this study is to assess the effects of a 3-month regimen of clopidogrel initiated with a loading dose (LD) of 300 mg followed by 75 mg/day during the first 21days versus a 3-month regimen of ASA 75 mg/day alone on reducing the 3-month risk of any stroke (both ischemic and hemorrhagic, primary outcome) when initiated within 24 hours of symptom onset in high-risk patients with TIA or minor stroke.

Inclusion criteria:

1. Adult subjects (male or female ≥ 40 years)
2. Acute non-disabling ischemic stroke (NIHSS≤3 at the time of randomization) that can be treated with study drug within 24 hours of symptoms onset. Symptom onset is defined by the "last see normal" principle.
3. TIA (Neurological deficit attributed to focal brain ischemia, with resolution of the deficit within 24 hours of symptom onset), that can be treated with study drug within 24 hours of symptoms onset and with moderate-to-high risk of stroke recurrence (ABCD2 score ≥ 4 at the time of randomization). Symptom onset is defined by the "last see normal" principle.
4. Informed consent signed

Primary Efficacy Endpoint:

Percentage of patients with the 3-month new vascular events, defined as any event of the following:Any stroke (ischemic or hemorrhage).

Inclusion criteria:

• Adult subjects (male or female≥40 years)
• Acute non-disabling ischemic stroke (NIHSS≤3 at the time of randomization) that can be treated with study drug within 24 hours of symptoms onset. Symptom onset is defined by the "last see normal" principle
• TIA (Neurological deficit attributed to focal brain ischemia, with resolution of the deficit within 24 hours of symptom onset), that can be treated with study drug within 24 hours of symptoms onset and with moderate-to-high risk of stroke recurrence (ABCD2 score≥4 at the time of randomization).Symptom onset is defined by the "last see normal" principle
• Informed consent signed

Exclusion Criteria:

• Diagnosis of hemorrhage or other pathology, such as vascular malformation, tumor, abscess or other major non-ischemic brain disease (e.g., multiple sclerosis) on baseline head CT or MRI
• Isolated or pure sensory symptoms (e.g., numbness), isolated visual changes, or isolated dizziness/vertigo without evidence of acute infarction on baseline head CT or MRI
• Modified Rankin Scale Score>2 at randomization (pre-morbid historical assessment)
• NIH Stroke Score≥4 at randomization
• Clear indication for anticoagulation(presumed cardiac source of embolus, e.g., atrial fibrillation, prosthetic cardiac valves known or suspected endocarditis)
• Contraindication to clopidogrel or ASA
• Known allergy
• Severe renal or hepatic insufficiency
• Severe cardiac failure, asthma
• Hemostatic disorder or systemic bleeding
• History of hemostatic disorder or systemic bleeding
• History of thrombocytopenia or neutropenia
• History of drug-induced hematologic or hepatic abnormalities
• Low white blood cell (<2 x109/l) or platelet count (<100 x109/l)
• Use of thrombolysis within 24 hours prior to randomization
• History of intracranial hemorrhage
• Anticipated requirement for long-term non-study antiplatelet drugs, or NSAIDs affecting platelet function
• Current treatment (last dose given within 10 days before randomization) with heparin therapy or oral anti coagulation
• Gastrointestinal bleed or major surgery within 3 months
• Planned or likely revascularization (any angioplasty or vascular surgery) within the next 3 months (if clinically indicated, vascular imaging should be performed prior to randomization whenever possible)
• Scheduled for surgery or interventional treatment requiring study drug cessation
• Qualifying TIA or minor stroke induced by angiography or surgery
• Severe non-cardiovascular comorbidity with life expectancy < 3 months
• Women of childbearing age not practicing reliable contraception who do not have a documented negative pregnancy test
• Currently receiving an investigational drug or device