In 40 female ASA class I-II patients, scheduled for laparoscopy, midazolam 0.2 mg kg-1 i.v. was compared with thiopentone 5 mg kg-1 i.v. for induction of anaesthesia after parenteral premedication. Loss of the eyelash reflex occurred significantly earlier (p less than 0.005) in the thiopentone group (23.3 s) than in the midazolam group (37.5 s). During orotracheal intubation a more stable cardiovascular course was found with midazolam than with thiopentone. Awakening was markedly slower with midazolam than with thiopentone. Anterograde amnesia of more than 60 minutes after induction of anaesthesia occurred in 50% of midazolam patients compared with 10% in the thiopentone group. No significant differences in side effects could be found. Midazolam 0.2 mg kg-1 was sufficient to induce anaesthesia reliably after premedication with droperidol and fentanyl shortly before induction.