This study compares the induction and recovery characteristics, haemodynamic changes and side effects of propofol, thiopentone and midazolam when used as the anaesthetic agents for cardioversion. Recovery after midazolam was significantly longer (p less than 0.05) than with either thiopentone or propofol. There was no difference in the recovery times between thiopentone and propofol. There was a significant decrease in mean arterial pressure 2 minutes after induction with propofol and midazolam. Three patients each in the thiopentone and propofol groups needed assisted ventilation because of apneoea, and four patients each in the propofol and midazolam groups had low Spo2 values (less than 95%). Flumazenil was used to reverse the effects of midazolam in eight patients and five of these were still drowsy 4 hours after the procedure. This study indicates that thiopentone is the most satisfactory agent for anaesthesia for cardioversion.