Whether acute anticoagulation after cardioembolic stroke affords substantial protection against early recurrent emboli or an unacceptable risk of hemorrhage remains controversial. To assess this further, we evaluated 121 consecutive patients with acute cardioembolic stroke. Forty-nine were therapeutically anticoagulated within 96 hours of stroke onset, and 41 received no anticoagulants within the first 2 weeks after stroke. These two groups did not differ significantly with regard to age, sex, severity of acute neurologic deficit, or spectrum of underlying cardiac disease. The incidences of clinically significant brain hemorrhage (2%) and early recurrent embolization (2%) were equally low in both groups. Our data suggest that acute acute anticoagulation may be employed safely in most patients with cardioembolic stroke but that such treatment does not clearly benefit this population as a whole.