The banning of mercury from clinical practice will lead to the inevitable demise of traditional clinical sphygmomanometry. There are differences in approach to this important issue between European countries on the one hand, which generally have accepted that the mercury sphygmomanometer must be replaced with alternative devices, and the U.S. on the other, where the view is that the mercury sphygmomanometer should remain as the mainstay of blood pressure measurement. The availability of alternative devices for the mercury sphygmomanometer is improving but the problem of independent validation is a serious issue, which is being addressed by the European Society of Hypertension Working Party on Blood Pressure Monitoring, which has drafted an International Protocol for validating blood pressure measuring devices. The removal of the mercury sphygmomanometer from clinical practice has other implications, which merit careful consideration; the advent of automated devices must lead inevitably to the disappearance of the traditional clinical auscultatory technique of blood pressure measurement, and with the disappearance of mercury it will be argued that theSystème International(SI) unit of measurement – the kilopascal – should replace the millimetre of mercury.