We evaluated immediate anticoagulation of embolic stroke. Of 39 patients suffering a focal cerebral ischemia caused by a cardiac embolus, 38 were submitted to CT within 24 hours after onset. Twenty-one patients received direct full anticoagulation and, in 10 patients, treatment was delayed because of hemorrhagic infarction on initial CT (3 cases), cardiac cause 24 hours or more after stroke onset, or treatment delay without specific reason (6 cases). Eight patients with severe deficit were not anticoagulated because of hemorrhagic signs on initial CT, impaired consciousness, or general contra-indications to such treatment. Twenty-one follow-up CT-scans were performed under full anti-coagulation, and in only 2 cases hemorrhagic infarction was noticed without clinical deterioration. No clinical worsening attributable to anticoagulant treatment was observed during the three week observation period. It is concluded that direct anticoagulation therapy does neither induce hemorrhagic infarction nor cerebral hemorrhage in patients with embolic stroke nor does it cause clinical deterioration.