Epilepsy is one of the major neurological disorders, affecting roughly 1-2% of the world's population, of which approximately 20-25% of patients are drug resistant. A variety of drugs have been used to activate and identify the epileptic area in patients during presurgical evaluation. We studied the cerebral blood flow (CBF) by single photon-emission computed tomography (SPECT) and bioelectrical brain activity responses to etomidate in 11 patients. Etomidate (0.1 mg/kg) was administered while patients were monitored by video-electroencephalography with foramen ovale electrodes (FOEs). After etomidate administration, a brief period of high-frequency activity was observed, followed by a generalized, high-voltage delta pattern. Increased regional CBF was observed bilaterally in thalamus, putamen, and posterior hippocampus. Besides, the only interhemispheric difference was observed in the posterior hippocampus, where CBF decreased in the epileptic temporal lobe. Activation by etomidate induces a specific and repetitive response in the bioelectrical activity. In addition, CBF changes induced by etomidate may serve as a diagnostic tool in the near future.