To evaluate the redistribution phenomenon on delayed I-123 IMP SPECT images of children and adolescents with partial seizures, 25 patients were selected and investigated in the interictal state. Early and delayed SPECT were performed 15-20 minutes and 5 hours, respectively, after I-123 IMP injection. Redistribution patterns were classified into three groups: 1) redistribution (RD) (-) group (n = 5), in which a low-uptake area on the early image persisted or was enlarged on the delayed image, 2) RD (+) group (n = 14), in which a low-uptake area on the early image changed to normal distribution on the delayed image, and 3) marked redistribution (MRD) (+) group (n = 6), In which a low-uptake area on the early image changed to a high uptake area on the delayed image. Among the patients who were followed for at least 12 months after the SPECT scans, the short-term clinical outcome tended to be good in the RD (+) group, intermediate in the MRD (+) group, and poor in the RD (-) group. These results of our preliminary comparative study indicate that the redistribution pattern of I-123 IMP may be related to the clinical aspects in patients with partial seizures and that it may play an important role in predicting their short-term clinical outcome.