Background : Epidural pressure is reported to change in accordance with intracranial pressure (ICP). As ICP changes during general anesthesia, it is also possible that epidural pressure may change during general anesthesia. The aim of this study was to obtain trends of epidural pressure change during general anesthesia. Methods: Eighteen patients scheduled for gastrectomy were allocated for this study after obtaining informed consent. Epidural catheter was inserted at T7-8, T8-9 interspace before induction. Catheter was connected to a pressure transducer after calibration. General anesthesia was induced with thiopental sodium (5 mg/kg), succinylcholine (1 mg/kg), followed by 3% enflurane. Anesthesia was maintained with 50% N2O in oxygen and 1∼2% enflurane with vecuronium (0.1 mg/kg). Each patients was mechanically ventilated with tidal volume of 10 ml/kg at a rate of 10 bpm. Epidural pressure was measured before induction, at the time of injection of thiopental sodium, succinylcholine, laryngoscopy, intubation, surgical incision, and 30 minutes after surgical incision. Stastical analysis was done using repeated measures of ANOVA with Helmert option (p＜0.05). Results : Epidural pressure significantly changed dynamically during general anesthesia. Epidural pressures increased at intubation and at 30 minutes after surgical incision when compared with those at the time of laryngoscopy and incision, respectively (p＜0.05). Conclusion : Our study indicates that epidural pressures changes dynamically during induction period of general anesthesia and also showed possibility that epidural pressure monitoring could be used instead of more invasive direct ICP monitoring. (Korean J Anesthesiol 1999; 36: 232∼238)