Speech lateralization was assessed in 25 patients with epilepsy by direct carotid injection or carotid catheterization from a femoral approach. Hemispheric anesthesia was induced by intracarotid injection of the rapidly acting barbiturate methohexital. This technique allowed same-day study of both hemispheres, permitted repeated injection of either carotid artery without accumulation of methohexital sufficient to cause systemic effects, and added little to the total time required for three-vessel cerebral angiography. Unilateral seizures were induced by methohexital injection in 4 patients. No other complication secondary to the methohexital study was observed.