Sequential examinations of single photon emission computed tomography (SPECT) were performed on a 5-month-old boy with acute infantile hemiplegia from the acute ictal stage. SPECT was performed with technetium-99m-hexamethyl-propylene-amineoxime during the status when the patient had left-hemiconvulsions (status epilepticus) and on the 3rd, 7th and 10th day after the status. During the ictal stage and the 3rd day after the status, diffuse hyperperfusion was revealed in the right hemisphere, while diffuse hypoperfusion was exhibited in the right hemisphere on the 7th and 10th day after the status. Hypoperfusion in the corresponding hemisphere, after the status, has been reported in patients with acute infantile hemiplegia. There has, however, been no report of ictal brain perfusion. The pathogenesis of this hyperperfusion is not clear, but alteration of brain perfusion in this patient, especially in acute phase, may help to elucidate the etiology of acute infantile hemiplegia.