Background : Clonidine has been regarded as an adequate supplementary anesthetic during epidural anesthesia and has been used with local anesthetics such as bupivacaine or lidocaine to support the effects of these anesthetics . The authors would examine whether clonidine is an adequate supplementary anesthetic when it is used with ropivacaine during epidural anesthesia. Methods : Thirty - two healthy patients undergoing a hip or lower limb surgery were divided into two groups. In group 1, 0.5% ropivacaine 15 ml was administered . In group 2 , 0.5% ropivacaine 15 ml combined with clonidine 150㎍ was administered . Onset , duration and maximal height of sensory block were assessed. Sedation score , blood pressure and heart rate were measured. Results : Duration of sensory block of group 2 was significantly longer than that of group 1. Sedation score of group 2 was significantly higher than that of group 1. Blood pressure of group 2 was significantly lower than that of group 1 at 50 min, 70 min and 90 min after epidural injection. No significant differences were observed in onset of sensory block and heart rate between the two groups . Conclusions : The addition of clonidine to ropivacaine during epidural anesthesia prolonged duration of sensory block and produced useful sedation . It caused relatively stable hemodynamic changes . These results suggest that clonidine is an adequate supplementary anesthetic when it is used with ropivacaine during epidural anesthesia. ( Korean J Anesthesiol 2001 ; 41: 428 - 433 )