The relationship between the rCBF and EEG frequency content was investigated in the contralateral hemisphere of 22 patients with acute cerebral infarction in the territory of the carotid artery. The degree of rCBF reduction was mild, moderate or severe and ranged between 6 to 80% from the lowest age matched normal values obtained in this laboratory. The EEG frequency indices were always lower over the infarcted hemisphere than over the contralateral one, ranging from 4.2 to 13.0 c/s, mean 6.0 c/s. The indices obtained over the opposite hemisphere ranged from 4.7 c/s to 14.5 c/s, mean 9.3 c/s. No significant correlation (p=0.89) was found between the 'age free rCBF' and the EEG frequency indices of the contralateral hemisphere of patients with acute ischemic stroke. (The correlation was found to be negative at the level of r=0.235).