Midazolam is a short-acting water soluble benzodiazepine derivative. It is a hypnotic used for intravenous anaesthesia induction. The present investigation was designed in a prospective double-blind fashion to compare midazolam with thiopentone as hypnotic components in balanced anaesthesia. The study included 50 healthy patients undergoing relatively short surgical procedures. The results revealed that thiopentone is faster in onset than midazolam for induction of anaesthesia, with less variation of dose response. However, maintenance of anaesthesia was superior with midazolam, requiring fewer supplemental anaesthetic drugs, having better patient acceptance and providing more amnesia. Postoperative complications were very low with both techniques. Midazolam was surprisingly similar to thiopentone in most parameters including emergence time from anaesthesia. Midazolam is a new drug with potential both for induction of anaesthesia and maintenance of balanced anaesthesia. © 1979 Canadian Anesthesiologists.