A comparative study of SPECT,BEAM, EEG and CT in the localization of epileptogenic focus is reported in 40 cases of intractable epilepsy. The majority of cases showed decreased rCBF and slow waves in the epileptogenic foci during inter-ictal periods. Localization rates of epileptogenic fool by SPECT and BEAM were higher than by EEG or CT. The results showed that vasidilating agents may be useful in the treatment of intractable epilepsy.