Though clinical use of verapamil, a calcium channel blocker, is increasingly presenting and hemodynamic change due to verapamil alone and in combination with beta b1ockerg or inhalation aneathetics are in active investgation now, there is scare Korean literature about the use of verapamil for the treatment of tachycardia during aneatheeia. Here, we report our clinical enflurance of dramatic, even dangerous, control of tachy-cardia during enflurane anesthesia in a patient with hyperthyroidism after trial of verapamil. There are two episodes of tachycardia in a 52-year old female with hyperthyroidism of 3-rearg duration and atrial fibrillation, each developed during enflurane anesthesia for 2 operations performed one moath apart. After slow intravenous injection of verapamil(0.1mg/kg for the first and 0.05 mg/kg for the second episode), the heart rates were reduced from 130 and 132 to 80 and 75. The effect was much sustained and the reduction of BP were slight in both instances. We feel that the dramatic reduction of heart rate is probably related to drug interaction between verapamil, propranolol given preoperatively, and enflurane. Literatures concerning the use of, and the heinodynamic changes induced by verapamil in various situations are reviewed briefly.