Tc-99m HMPAO SPECT brain imaging was performed interictally in thirty three patients with partial seizures. Identification of areas of low perfusion was by visual inspection in all patients and additionally in 16 patients quantitative values were obtained. SPECT results were compared with the EEG and CT. In 27 patients (82%). SPECT demonstrated decreased regional cerebral perfusion. Localised pathology in one hemisphere was shown in 21 patients with SPECT (63.6%), in 14 with EEG (42%) and in 9 with CT (27.2%). The areas that showed decreased perfusion were mostly correlated with EEG and/or CT findings. Tc-99m-SPECT can be useful in lateralisation of the epileptic area, especially in candidates for surgery.