This study represents the first prospective controlled investigation of preoperative versus postoperative (6 months) language function in patients who underwent partial resection of the dominant (n = 15) or nondominant (n = 14) anterior temporal lobe for treatment of medically refractory epilepsy. Language dominance was confirmed by intracarotid sodium amytal test. Thirteen of the 15 patients undergoing anterior temporal lobectomy of the dominant hemisphere were operated on under local anesthesia in order to map language and memory functions intraoperatively. Using a standardized language/aphasia battery, we found a significant trend of worse preoperative language function in patients with dominant hemisphere temporal lobe foci in comparison to patients with nondominant foci. Following anterior temporal lobectomy, neither group showed any significant losses in language function, whereas the dominant hemisphere temporal lobe group showed significant improvement in receptive language comprehension and associative verbal fluency.