This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized on electroencephalography, the regional neuronal activity expressed as rCBF unexpectedly was markedly asymmetrical in one of the cases. These findings demonstrated that the 99mTc-HMPAO technique makes it possible to discriminate intraictal variation in cortical and subcortical activation between the hemispheres during electroencephalography-verified generalized seizures.