A 2% solution of propofol has been compared with the 1% formulation for sedation in patients whose lungs were being mechanically ventilated in an intensive care unit following coronary artery bypass surgery. There were no significant differences in the amount of propofol used in the two groups, the rate of propofol infusion or the number of changes made to the infusion rate to maintain the desired level of sedation. Recovery times and times to tracheal extubation were similar. The mean heart rates of those receiving 2% propofol were significantly higher throughout the period of the study for no apparent reason. Propofol 2% was found to be safe, easy to administer and a practical alternative to the 1% solution for sedating cardiac surgical patients.