Korean J Anesthesiol Introduction The recent developments in intravenous anesthetics have allowed intravenous anesthetics to move from being com- plimentary to becoming the main anesthetics during surgery. Propofol and remifentanil’s context-sensitive half times are short. So, in the setting of total intravenous anesthesia, even when the anesthesia is performed over a long period of time, the recovery time is quite short compared to that of inhalational anesthetics [1]. Remifentanil is an opioid with one of the shortest context-sensitive half times. During endotracheal intubation, it inhibits the activation of the sympathetic nervous system and prevents increases of the blood pressure and heart rate. Much research has been done on the optimal dose for these effects [2]. There are many reports of clinical situations where certain dosage amounts of remifentanil suppressed the hemodynamic and cardiovascular responses from endotracheal intubation in hypertensive patients [3], elderly patients [4] and diabetic patients [5]. Smokers are known to have an extremely increased cardio- vascular response compared to that of nonsmokers [6,7]. Yet, there have hardly been any reports on the appropriate dosages of remifentanil for smokers and nonsmokers to repress the cardiovascular response to endotracheal intubation. For smokers, endotracheal intubation increases the myocardial oxygen demand, but it constricts the coronary artery, which elevates vascular resistance and reduces the blood flow rate [8]. So preventing the hemodynamic changes due to endotracheal intubation is very important. We attempted to determine if there is a difference between smokers and nonsmokers for their cardiovascular response to remifentanil that is administered for endotracheal intubation. Materials and Methods Eighty ASA I & II patients of both genders and whose ages were between 30 and 60 and the BMI ranged from 20 to 30 were enrolled in the study. In each gender group, there were 20 smokers and 20 nonsmokers. The gender groups were divided into male smokers (Group MS), male nonsmokers (Group MN), female smokers (Group FS) and female nonsmokers (Group FN), resulting in 4 subgroups. After the approval of the local ethics committee, the authors conducted a preanesthetic visit with the patients. The patients gave us their written informed consent after they were told of the purpose and methodology of the research. During the preanesthetic visit before surgery, the authors made inquiries about whether or not the patients were smokers. If they had a history of smoking for 2 or more years and they still smoked, then they were placed in the smoking www.ekja.org Sung, et al. group. The duration of smoking (in months) and the quantity of smoking (number of cigarettes per day) were recorded and we recommended that patients should stop smoking after the preanesthetic visit. If the patient had never smoked, then they were put in the nonsmoking group. Patients were excluded if they had hypertension, diabetes mellitus, neurological disorders or a past history of taking cardiovascular drugs such as beta blockers. Patients were excluded if they were expected to have difficult intubation or if they did not have successful endotracheal intubation on the first try. As premedication, 30 minutes before the surgery, intramu- scular injection was done with ranitidine (UrantacⓇ, Whanin, Korea) 25 mg and midazolam (DormicumⓇ, Roche, Switzerland) 2.5 mg. The patients were monitored during anesthetic induction with electrocardiography, noninvasive blood pressure measurement and a pulse oxymeter. Lactated Ringer' solution was administered as intravenous fluid with an 18 G angio needle in a forearm vein. For prehydration, 1/2 of the calculated maintenance volume (2 ml/kg/hr), with considering the NPO time, was infused before induction. Induction of anesthesia was done according to the methodology of Shim et al. [2] as follows. Remifentanil (UltivaTM, GSK, Italy) 1 mg was diluted with 50 ml of normal saline (20 μg/ml), and then using an infusion pump (Pilot C, Fresenius Vial, France), continuous infusion was started at a rating of 10 μg/kg/hr concomitant with administering 6 L/ min oxygen with a face mask for 2 minutes. Two minutes after remifentanil infusion, midazolam 0.05 mg/kg and propofol (ProviveTM, Claris, India) 0.8 mg/kg were administered by intravenous injection to induce unconsciousness. If the patient did not lose consciousness within 1 minute, then propofol 20 mg was additionally administered. The loss of consciousness was checked by the eyelash reflex. Rocuronium (EsmeronⓇ, Organon, Netherlands) 1 mg/kg was intravenously injected over a period of 10 seconds. After controlled ventilation for 2 minutes, endotracheal intubation was performed. Afterwards, the remifentanil infusion was reduced to 2 μg/kg/hr. With the control mode ventilation, anesthesia was maintained with sevoflurane 1.5% in O2 : Air = 1.5 L : 2.5 L/min, with a tidal volume of 10 ml/kg and a respiratory rate of 10 bpm. The measurements of the mean arterial pressure (MAP) and heart rate (HR) were done before anesthetic induction (baseline), at the time of just falling unconsciousness, just before endotracheal intubation, just after intubation and 1, 2 and 3 minutes after intubation. During anesthetic induction, when the systolic blood pressure fell below 80 mmHg, the administration of remifentanil was stopped. All the measurements are shown as the mean ± standard deviation. SPSS 17.0 (SPSS, Inc., Chicago, IL) was used for statistical analysis. The height, weight and the dosage of remifentanil and the total amount of infused propofol were 509