Inclusion Criteria:
* Patients must have a serious measurable neurological deficit on the NIH Stroke Scale due to focal brain ischemia.
* An NIH Stroke Scale score \>5 at the time the rt-PA is begun.
* Age: 18 through 85 years (i.e. candidates must have had their 18th birthday, but not had their 86th birthday).
* Intravenous rt-PA therapy must be initiated within 3 hours of onset of stroke symptoms.
Exclusion Criteria:
* History of stroke in the past 3 months.
* Previous intra-cranial hemorrhage, neoplasm, subarachnoid hemorrhage, or arterial venous malformation.
* Clinical presentation suggests a subarachnoid hemorrhage, even if initial CT scan is normal.
* Hypertension at time of treatment; systolic BP \> 185 or diastolic \> 110 mmHg or aggressive measures to lower blood pressure to below these limits are needed.
* Presumed septic embolus.
* Presumed pericarditis including pericarditis after acute myocardial infarction.
* Recent (within 30 days) surgery or biopsy of parenchymal organ.
* Recent (within 30 days) trauma, with internal injuries or ulcerative wounds.
* Recent (within 90 days) severe head trauma or head trauma with loss of consciousness.
* Any active or recent (within 30 days) serious systemic hemorrhage.
* Known hereditary or acquired hemorrhagic diathesis, coagulation factor deficiency; or oral anticoagulant therapy with International Normalized Ratio (INR) \> 1.7.
* Baseline lab values: positive urine pregnancy test, glucose \< 50 or \> 400 mg/dl, platelets \<100,000 /mm3, Hct \<25 %, or creatinine \> 4 mg/dl.
* Ongoing renal dialysis, regardless of creatinine.
* Subjects who received Low Molecular Weight heparins (such as Dalteparin, Enoxaparin, Tinzaparin) as deep vein thrombosis (DVT) prophylaxis or in full dose within the previous 24 hours.
* Subjects who received heparin or a direct thrombin inhibitor (such as bivalirudin, argatroban, or lepirudin) within 48 hours from screening must have had a normal partial prothrombin time (PTT).
* Subjects who received Factor Xa inhibitors (such as fondaparinux) or direct thrombin inhibitors (such as dabigatran) within the last 4 days.
* Arterial puncture at a non-compressible site or a lumbar puncture in the previous 7 days.
* Seizure at onset of stroke.
* Pre-existing neurological or psychiatric disease that would confound the neurological or functional evaluations.
* Other serious, advanced, or terminal illness or any other condition that the investigator feels would pose a significant hazard to the patient if rt-PA or eptifibatide therapy were initiated.
* Patients whose peripheral venous access is so poor that they are unable to have two standard peripheral intravenous lines started.
* Current participation in another research drug treatment protocol. Patient cannot start another experimental agent until after 90 days.
* Informed consent is not or cannot be obtained.
* Any known history of amyloid angiopathy.
* High density lesion consistent with hemorrhage of any degree.
* Significant mass effect with midline shift.
* Large (more than 1/3 of the middle cerebral artery) regions of clear hypodensity on the baseline CT scan. Sulcal effacement and/or loss of grey-white differentiation alone are not contraindications for treatment.