We studied white blood cell (WBC) count and erythrocyte sedimentation rate (ESR) in 241 consecutive patients with acute ischemic stroke. White cell count was elevated in 20% of the patients, ESR was elevated in 68%. Each increase significantly correlated with outcome, as evaluated by either lesion size at CT scan or by score at the Rankin disability scale at the time of discharge. This correlation was stronger for WBC count than for ESR. These routine blood tests may be useful adjuncts in determining stroke prognosis.