The haemodynamic changes following induction of anaesthesia with equipotent doses of propofol and thiopentone have been compared. Propofol caused a significant fall in arterial blood pressure and total peripheral resistance, with a slight fall in cardiac output. There were no changes in heart rate. Apart from an initial, but statistically insignificant increase in heart rate, similar changes were produced by thiopentone, but to a lesser degree. It is concluded that induction of anaesthesia with propofol results in acceptable haemodynamic changes, but that the agent is more depressant to the cardiovascular system than thiopentone.