It is known that anesthetic agents can influence the QTc. In addition, tracheal intubation during induction can stimulates sympathetic activity, which, as a results, prolong the QTc interval. Therefore, the aim of study is to find out the effect site concentration of remifentanil for preventing QTc interval prolongation during intubation under propofol-remifentanil anesthesia in normotensive and hypertensive patients.