BACKGROUND: Epidural anesthesia is becoming an increasingly important aspect of anaesthetic practice because it has many advantages. To achieve the appropriate sedation, various methods have been described. The authors applied the ketamine for this purpose in subanesthetic dose and compared with the midazolam that has been most commonly used for intravenous sedation. METHODS: Fifty-seven adult patients undergoing lower abdominal and extremity surgery who were receiving epidural anesthesia were randomely enrolled into this clinical study. They were allocated to three groups to receive only normal saline (group C), midazolam 0.05 mg/kg (group M) and ketamine 0.5 mg/kg midazolam 0.05 mg/kg (group K) in normal saline 10ml, respectively. Hemodynamic and respiratory measurements were recorded at baseline, 1 minute, 3 minute, 5 minute, 10 minute, 20 minute and 30 minute after sedation. The degree of sedation was assessed by a blinded observer using sedation score. RESULTS: There were no significant differences for hemodynamic and respiratory parameters, but decrements of arterial pressure at 1 minute after sedation were most remarkable in the group M. Sedation was satisfactorily achieved by combination of ketamine and midazolam without significant emergence reaction. CONCLUSIONS: The combination of ketamine and midazolam was judged to be suitable alternative for sedation during epidural anesthesia.