Inclusion Criteria:  age > 18, both sexes, acute ischemic stroke within 4.5 hours, NIHSS (5-25)  Exclusion Criteria:  Significant head trauma or prior stroke in the previous 3 months  Symptoms suggest subarachnoid hemorrhage Arterial puncture at a noncompressible site in previous 7 days History of previous intracranial hemorrhage Intracranial neoplasm, AVM, or an aneurysm Recent intracranial or intraspinal surgery Elevated blood pressure (systolic greater than 185 mmHg or diastolic greater than 110 mmHg) Active internal bleeding Acute bleeding diathesis, including but not limited to Platelet count less than 100 000/mm^3 Heparin received within 48 hours resulting in abnormally elevated aPTT above the upper limit of normal Current use of anticoagulant with INR greater than 1.7 or PT greater than 15 seconds Current use of direct thrombin inhibitors or direct factor Xa inhibitors with elevated sensitive laboratory tests (e.g., aPTT, INR, platelet count, ECT, TT, or appropriate factor Xa activity assays) Blood glucose concentration less than 50 mg/dL (2.7 mmol/L) CT demonstrates multilobar infarction (hypodensity greater than a one-third cerebral hemisphere) Relative Exclusion Criteria  Recent experience suggests that under some circumstances, with careful consideration and weighing of risk to benefit, patients may receive fibrinolytic therapy despite 1 or more relative contraindications. Consider the risk to the benefit of intravenous rtPA administration carefully if any of these relative contraindications are present:  Only minor or quickly improving stroke symptoms (clearing automatically) Pregnancy Seizure at the onset with postictal residual neurological impairments Major surgery or serious trauma within prior 14 days Recent GI or urinary tract hemorrhage (within previous 21 days)