In patients undergoing hypophysectomy through transsphenoidal approach, preventing cough during anesthetic emergence is important to avoid hemorrhage and cerebrospinal fluid leakage. Previous reports demonstrated that administration of remifentanil during anesthetic emergence could reduce the incidence and severity of cough during anesthetic emergence. Therefore, the objective of this study is to determine EC95 of remifentanil for preventing cough during anesthetic emergence in patients undergoing hypophysectomy with transsphenoidal approach.