There are two Study Sections: A and B

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Study Section A Inclusion Criteria:

1. acute ischemic stroke in an adult in-patient who can complete screening and begin study treatment within 6 hours of stroke onset (onset time defined as the last time the patient was known to be at his/her usual level of functioning)
2. patient not a candidate for rTPA treatment because treatment cannot be started within the required 3 hours after stroke onset, or because rTPA treatment is refused.

Study Section A Exclusion Criteria:

1. intracranial hemorrhage;
2. subfalcine, transtentorial, or foramen magnum herniation on CT or MRI scan of the brain;
3. history of hypersensitivity or intolerance to or toxicity from enoxaparin, other heparinoids, heparin, minocycline, or other tetracyclines;
4. weight 125lbs or less;
5. active bleeding;
6. thrombolytic treatment or major surgery in the previous 24 hours;
7. anticipated need for treatment with coumarin, or a low-molecular weight heparin other than enoxaparin, or unfractionated heparin before 36 hours after stroke onset (but see deep venous thrombosis prophylaxis, below);
8. INR above the normal range;
9. known coagulopathy;
10. platelet count <100,000/mm3 (if the count drops below 100,000 while on enoxaparin, the medication will be stopped)
11. pregnancy or lactation;
12. undergoing dialysis; severe renal impairment (creatinine clearance known or estimated to be <30ml/min);
13. mean arterial BP (taken to be 1/3 of the difference in mm Hg between diastolic BP and systolic BP, added to the diastolic BP) of 130 mm Hg or greater; (if the mean arterial BP is 130 mm Hg or greater but can be reduced by treatment to < 130 mm Hg, with systolic BP in the 150 169 mm Hg range, the patient may be entered).

Patients in Study Section A will be randomly assigned to one of the four treatment arms: enoxaparin, minocycline, enoxaparin and minocycline, or no intervention.

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Study Section B Inclusion Criteria:

1. acute ischemic stroke in an adult in-patient who can complete screening and begin study treatment within 24 hours of stroke onset (onset time defined as the last time the patient was known to be at his/her usual level of functioning;)
2. patient does not qualify for, or declines to participate in, Study Section A.

Study Section B Exclusion Criteria:

1. acute primary intracranial hemorrhage;
2. subfalcine, transtentorial, or foramen magnum herniation on CT or MRI scan of the brain;
3. pregnancy or lactation.

Patients in Study Section B will be randomly assigned to one of TWO treatment arms: minocycline, or no intervention.