In patients premedicated with scopolamine + morphine (+5 mg nitrazepam the evening before surgery), the sleep-inducing effect of midazolam 0.15 mg/kg i.v. was clearly slower in onset than that of thiopentone 4.67 mg/kg i.v. Somewhat fewer cardiovascular and local sequelae were found in the midazolam group, but, although apnoea occurred less often in the midazolam group it lasted longer. On the whole, the differences between midazolam and thiopentone had no apparent clinical consequences. Midazolam is a new alternative agent for induction in combination anaesthesia.