A simple, manually controlled infusion scheme for continuous administration of propofol was derived by simulation of a computer algorithm designed to achieve a predetermined blood concentration of propofol within 2 minutes and to maintain a constant blood level for the duration of surgery. The manual infusion scheme for a target blood propofol concentration of 3 micrograms/ml, consisted of a loading dose of 1 mg/kg followed immediately by an infusion of 10 mg/kg/hour for 10 minutes, 8 mg/kg/hour for the next 10 minutes and 6 mg/kg/hour thereafter. An overall mean blood propofol concentration of 3.67 micrograms/ml was achieved within 2 minutes and maintained stable for the subsequent 80-90 minutes of surgery. The decrease of systolic and diastolic arterial pressures at induction was much less than that previously described after larger induction doses of propofol and there was a negligible haemodynamic response to laryngoscopy and intubation or to the subsequent surgery. The quality of induction and maintenance of anaesthesia was satisfactory in every patient.