The cardiovascular and CNS effects of MIDAZOLAM 0.25 mg/kg were studied in 40 patients, randomised and emergency operations(20 males and 20 females). The effects of the administration of MIDAZOLAM intravenously on the cardiovascular and central nervous system were determined. The results were as follows: 1) It had short duration of action and absence of vascular irritation compared with MIDAZOLAM. 2) Three minutes after injection, mean systolic pressure decreased from 132±16 mmHg to 115±18 mmHg and diastolic pressure from 87±11mmHg to 77±13 mmHg. One minute after injection heart rate increased from 89±19 beat/min to 95±20 beat/min and after three minutes returned to prior level. 3) Our study shows that the intraveous administration of MIDAZOLAM 0.25mg/kg produces. a statistically significant, but clinically unimportant, decrease in blood pressure and an increase in heart rate. 4) The effects of MIDAZOLAM on the central nervous system were determined from the time of onset of injection. Spontaneous eye closure, loss of eyelash reflex and apnes were observed at 113±66 sec, 133±65 sec, and 147±58 sec, after injection of MIDAZOLAM. 5) MIDAZOLAM as an induction agent for anesthesia is not indicated for in out-patient surgery due to the extended duration of drowsiness losting over 3 hours in the recovery room. 6) MIDAZOLAM was sufficient as an induction agent for general anesthesia.