Cerebellar and cerebral subcortical blood flow in 41 children with partial epilepsy and 6 normal controls was investigated during the interictal state using single photon emission computed tomography with technetium-99m hexamethylpropyleneamineoxime. Seventeen of 41 patients had been treated with antiepileptic drugs (AEDs) for 4.65 +/- 3.80 years (range 0.2-12) and 24 patients were drug-free, Unilateral hypoperfusion of cerebellum and cerebral subcortical gray matter was demonstrated in 11 (28%) and 16 (40%) patients, respectively. Most of them also had focal cerebral cortical perfusion abnormalities, ipsilateral or contralateral to the cerebellar and cerebral subcortical hypoperfusion. The mean asymmetry indices of cerebellar blood flow in the medicated and the unmedicated patients were significantly higher than in the control cases (P < 0.02 and P < 0.04), whereas the differences in the asymmetry indices in cerebral subcortical areas were insignificant. AED therapy did not affect the perfusion of cerebellum and cerebral subcortical regions (P > 0.05 and P > 0.05), Our results suggest that functional alterations on anatomically connected remote areas in patients with partial epilepsy are not related to the drug effect and probably due to primary epileptogenic activity.