The influence of clonidine on the analgesic effect of epidural fentanyl was investigated in 45 patients who underwent total abdominsl hysterectomy by epidural admistration of fentanyl 100 g alone, clonidine 150ug alone, or in combination of the two drugs. Changes in the mean arteral pressure and pulse rate were observed after drug administration, and the analgesic effects was assessed by measuring analgesic duration, pain score, sedation score, and side effects. Analgesic duration was prolonged with improved quality by adding 150 ug of clonidine to 100 ug of epidural fentanyl. Mean arteral pressure and pulse rate were decreased more in fentanyl plus clonidine group than each drug alone group. But these changes were restored rapidly by injection of small dose of vasopressor. The clonidine alone group showed the least analgesic effect among three groups indicatings that clonidine would not be a sole analgesic agent and would be used as an adjunct to other opiate such as fentanyl.