30 cases receiving epidural anesthesia for lower extremities and abdominal surgery were selected in this study. Their physical status and average age were ASA I or II and 41 +/- 10.0 years old. Premedication included intramuscular injection of pethidine, atropine and promethazine. Epidural anesthesia was accomplished with 15 ml 2% lidocaine with epinephrine (1:80,000). After the stabilization of vital signs, the patients were put asleep by 0.1 mg/kg of midazolam intravenously. They were then evaluated by the sedative, cardiovascular, respiratory and recovery effects of intravenous midazolam in epidural anesthesia. The results were as follows: The patients receiving IV midazolam averagely fell asleep in 61.6 +/- 20.5 seconds and maintained asleep for 55.4 +/- 12.7 minutes. Pain on injection was not noted in these cases. Cardiovascular parameters revealed midazolam with general depression on systolic pressure (17.4 +/- 7.3%), diastolic pressure (13.4 +/- 8.4%), mean arterial pressure (12.7 +/- 7.0%), heart rate (10.9 +/- 7.2%), stroke volume (13.7 +/- 8.9%) and cardiac output (18.4 +/- 7.0%) respectively. The peak depression reached around 10 minutes after drug administration. Respiratory parameters dropped with SaO2 (1.1 +/- 1.6%) and respiratory rate (9.7 +/- 5.7%) and fell into trough after 5 minutes of drug administration. Although all the above parameters measured were statistically significant, they were of no clinical importance that required further management. No case had delirium, anxiety and vomiting in the recovery period. Conclusively, patients receiving epidural anesthesia with supplement of intravenous midazolam provides a good sedative effect. Clinically, there was less severe untowards reaction either in cardiovascular or respiratory systems. Smooth and stable recovery was also noted.(ABSTRACT TRUNCATED AT 250 WORDS)