We report a case in which WPW (Wolff-Parkinson-White)-type preexcitation syndrome arose unexpectedly immediately after induction of general anesthesia on a 25-yr-old man who had another rare cardiac arrhythmia, parasystole. His preoperative ECG showed ventricular bigeminy and a delta wave was observed after induction of anesthesia with fentanyl, midazolam and propofol. Anesthesia was maintained with propofol, fentanyl and nitrous oxide. The intraoperative ECG showed varying and temporary responsiveness to drugs such as atropine, lidocaine and ephedrine. After we started to infuse the dobutamine, the delta wave, ventricular bigeminy disappeared on the intraoperative ECG. We should consider the influence of anesthesia-related agents on arrhythmia, and aim to prevent and manage tachyarrhythmias caused by this syndrome. (Korean J Anesthesiol 1999; 37: 1143∼1148)