Ten infantile spasms (IS) patients had single photon emission computed tomography (SPECT) with [99mTc]HMPAO, EEG, and magnetic resonance imaging (MRI) studies. SPECT showed localized cerebral hypoperfusion in 7 infants (4 unifocal; 3 multifocal) always involving the temporal regions either unilaterally or bilaterally. EEGs obtained in near time of the SPECT studies showed focal abnormalities in all 7 infants with hypoperfusion on SPECT, with complete correspondence of the abnormalities in 5. MRI showed localized cerebral lesions in only 3 of the 10 infants, all of whom had corresponding areas of hypoperfusion on SPECT. Our study indicates that localized cerebral abnormalities (especially of the temporal lobes) may often be associated with IS and that such patients may have localized cerebral hypoperfusion on SPECT even when the MRI is normal.