Problems related to agitation in the ICU patients include cardiorespiratory instability, ina bility to cooperate with nursing care, failure to maintain op timal positioning in bed, dis- ruption of life sustaining tubes and catheters, and injuries to patients and hospital person- nel. Thus, the ability to provide safe, controllable, and reversible sedation can be important in the care of critically ill patients. Midazolam is a water soluble imidazobenzodiazepine with a rapid onset of ac tion and short elimination half life compared with diazepam or lorazepam. We evaluated the use of midazolam by continuous infusion for prolonged sedation of critically ill adult patients. The results were as follows ; 1) Midazolam infusion effectively controlled severe agitation in all patients. 2) No episodes of cardiovascular depression due to midazolam occur red during the study period. 3) In one patient, tolerance was developed 6 days after infusion. 4) Mean time to alertness was 2.23 hours. 5) In a renal failure patient, there was no significant prolongation of time to alertness. These results suggest that midazolam infusion provides safe, controllable, and reversible sedation in the care of critically ill patients.