Cerebral functional imaging methods provide information on the location of the epileptic focus in partial epilepsy of adults. We report our experience of one of these methods, single photon emission computed tomography (SPECT), in epilepsy of children. SPECT enables the regional cerebral blood flow (rCBF) to be measured, after inhalation or injection of 133-Xenon, on 5 contiguous, 20 mm thick axial sections, with a 14 mm resolution and negligible brain irradiation. In Sturge-Weber syndrome (13 patients aged 9 months to 18 years) the rCBF was reduced in the same territory as CT abnormalities suggesting ischaemia of the brain tissue lying below the pial angioma; the SPECT image facilitated the diagnosis in 3 patients with atypical CT. In hemimegalencephaly (6 patients aged 1 month to 10 years) the rCBF was extremely low in the hypertrophic hemisphere and in 1 case the SPECT image was determinant in the decision to perform hemispherectomy. In partial epilepsy with normal CT and/or MRI (42 children aged 1 to 15 years) the rCBF was abnormal in 83% of the patients, and its abnormality was located in the same area as the EEG focus in three quarters of the cases. Between seizures, the rCBF was low in 3 out of 4 cases and abnormality decreased after the seizures had ceased (6 patients explored twice); it was high in 1 out of 4 cases. Thus, in children as in adults, cerebral functional imaging provides new data which contribute to the localization and follow-up of epileptic foci.