Treatment of acute stroke is still difficult and the only specific drug approved (rtPA) can only be administered if treatment starts within 3 hours after onset of symptoms. This results in a still too small number of patients treated with rtPA ( < 15% in best clinical care institutions ). Ancrod is a differently acting biological drug which has been used for a long time but not for acute stroke treatment. STAT was the first RCT of medium size to show a significant benefit/risk ration if treatment starts within 3 hours. ESTAT was designed closely related to STAT but with a longer 6 hours window and specifically extended inclusion/exclusion criteria to avoid secondary complications possibly related to a longer time window.

Inclusion Criteria:

• 18 years and above, both sexes
• Acute ischemic stroke with first symptoms within 6 hours of beginning
• Treatment after onset of symptoms
• SSS < 40 at baseline ( consciousness necessary )

Exclusion Criteria:

• Clinical or CT evidence of brain hemorrhage or hemorrhagic transformation
• CT evidence of major signs of developing infarction
• Coma
• Prior strokes within 6 weeks
• Severe hypertension (> 220 systolic > 120 mm Hg diastolic)
• Baseline fibrinogen < 100 mg/dL
• Recent use of thrombolytic agents
• Recent or anticipated surgery