Experimental data showed that morphine interfered with calcium influx in the central nervous system and some calcium channel blockers potentiated analgesic effect of morphine. As few clinical data are available, we studied the effect of the calcium channel blocking agent, verapamil, on the analgesic effect of epidural morphine for postoperative pain control after upper abdominal surgery. The mean analgesic duration of 2mg of morphine was 17.9±4.3 hours and the addition of 5 and 10 mg of verapamil increased the analgesic effect of morphine significantly(28.2±6.1 hours and 26.7±6.3 hours, respectively). The quality of analgesia was improved by verapamil without significant changes in respiratory and cardiovascular functions. The data suggested that verapamil might be a useful adjunct to epidural morphine as a balanced analgesia for postoperative pain control, especially in certain patients such as the patient with coronary artery disease.