The pharmacokinetics of midazolam was studied in 21 children undergoing elective surgery at five different dose levels for induction of general anesthesia and were compared with a control group (n = 6) given thiopental, 5 mg/kg. The clearance of midazolam was found to be dose-related. The elimination half-life varied from 0.79 to 2.83 hr, which is shorter than in adult patients. Even a dose of 0.6 mg/kg midazolam was found to be unreliable as an agent for induction of anesthesia. Compared with thiopental 5 mg/kg, significantly longer times of onset to closing of the eyes (P less than 0.01) and the disappearance of eyelid reflex (P less than 0.01) were seen with midazolam.