Many agents such as analgesics and sedatives have been used to decrease pain, anxiety and awareness during anesthesia. The effects of midazolam and propofol on cardiopulmonary functions and sedation were evaluated in a clinical study during spinal anesthesia. Thirty adult patients were received either midazolam 0.05mg/kg IV or propofol 1.25mg/kg IV after spinal anesthesia. Minute volume, arterial oxygen saturation, blood pressure, and heart rate were checked before and 20min after spinal anesthesia, as well as 2 min, 5 min, 10 min, 30 min, 60 min after each drug administration. The results were as follows ; 1) Minute volume and SaO2 were decreased from 2 min to 10 min in each group. 2) Mean arterial pressure was decreased from 2 min to 60 min in each group, but there was no significant difference between the two groups. Heart rate was increased at 2 min in propofol group 3) Recovery time from sedation was faster in the propofol group than the midazolam group. From the above results, we have concluded that midazolam and propofol have some effects on cardiopulmonary function and many advantages if used carefully during spinal anesthesia.