The Wada test was performed for lateralization of language and memory function, using intracarotid injection of Sodium Amytal. But, the internal caroticd carotid artery (ICA) Wada test has some limitations for testing memory function. The posterior cerebral artery(PCA) Wada test has been designed to modify the ICA Wada test for testing memory function selectively. In our study, 10 patients out of 12 patients with intractable seizure underwent only the ICA Wada test and the other 2 patients underwent both the ICA and the selective PCA Wada test. In all 12 patients undergoing the ICA Wada test, we succesfully localized speech and language dominace. Four of 12 patients who underwent the ICA Wada test for evaluation of memory function displayed superior memory functions in one hemisphere, but the other hemisphere also significantly contributed to memory. The selective PCA Wada test, performed in 2 patients, showed successful results of memory function test in both patients. Four o 12 patients underwent temporal lobectomy and there was no major post-operative language or memory deficits. We conclude that the ICA and PCA Wada tests are useful for preoperative evaluation of medically intractable epilepsy, and the PCA Wada test is valuable in memory evaluation in some patients who have hight risk of postoperative global amnesia after temporal lobectomy following equivocal results of memory function by the ICA Wada test.