d-Tubocurarine(d-TC) causes hypotension, probably as a result of the liberation of histamine; in larger doses, it produces ganglionic blockade. An increase of histamine levels in plasma to 200 to 300 percent of baseline causes a brief decrease in arterial blood pressure(1 to 5 minutes) and the increase in heart rate. The amount of histamine released by d- TC is dose related and is also related to speed of injection. Therefore histamine release can be minimized by the slow administration, light level of surgical anesthesia, and the use of smaller doses. Thus, the purpose of this study was to prevent the cardiovascular effect of d-TC by the slow administration undergoing general anesthesia. The study population was from 40 patients scheduled for elective surgery at Yeungnam University Hospital, who belonged to physical status I or II of ASA classification. Patients were divided into 4 groups by speed of injection of 10, 30, 60 and 120 seconds(group 1, 2, 3 and 4, respectively). All patients were premedicated with hydroxyzine 1mg/kg, glycopyrrolate 0.2mg, and fentanyl 1 ug/kg IM 30 minutes before anesthesia. Patients were induced with thiopental sodium 4-5 mg/kg until the disappearance of lid-reflex. Succinylcholine 1.0 mg/kg IV was used to facilitate endotracheal intubation. As soon as relaxafion was complete, laryngoscopy was initiated. After the completion of intubation, nitrous oxide and 50% oxygen with 0.6% halothane was administrated. The blood pressure and heart rate were measured using noninvasive automatic blood pressure manometer for 60 minutes per 1 minute. Data were analyzed with one-way ANOVA test within the groups. p<0.05 was considered significant. The results were as follows, The changes of blood pressure was decreased in rapid injection groups(Group 1 2) compared with slowly injection groups(Group 3 & 4) at 2 min, 5 min after d-TC administration. The changes of heart rate was significantly increased(p<0.05) at 1min, 2 min after d-TC administration in rapid injection groups compared with slow injection groups. These results show that the cardiovascular effect of d-TC might be prevented by slowly administration undergoing general anesthesia.