Twenty-one children with various seizure disorders were studied using Tc-99m HMPAO brain SPECT, cranial CT, and electroencephalography (EEG). The rates of pathologic findings on SPECT, CT, and EEG were 67%, 38%, and 52%, respectively, SPECT showed congruent, or more extensive, lesions in all eight patients with CT lesions. Six of the 13 children who had normal CT results, had abnormal SPECT study results, In this postictal series, 4 of the 14 abnormalities detected in the first SPECT study that was applied within 24 hours of a seizure, were in the form of hyperperfused areas. Eight of the 14 abnormal first SPECT studies had become normal by the second SPECT. We conclude that, with respect to the depiction of some kind of abnormality, HMPAO brain SPECT is superior to CT and EEG, and considerable changes in brain perfusion are likely to occur over a period of a few weeks.