This short guide is designed to provide step-by-step instructions for the safe substitution of non-mercury thermometers and sphygmomanometers in health-care settings. It identifies the resources available to provide confidence that the substituted products will provide equivalent accuracy and comparable clinical utility, while protecting health-care workers and the environment. It is designed for professionals responsible for institutions or ministries desiring to switch to safer non-polluting technologies in health care. This guide is also an output of a global mercury-free health-care initiative in which WHO is engaged. This global initiative promotes the substitution of mercury-based medical devices with safe, affordable, accurate alternatives around the world. The global mercury-free health-care initiative has documented mercury substitution in dozens of countries. It has also produced a series of additional resources for health professionals, health-system managers and government officials that can be useful in developing and implementing policy and strategies for mercury substitution in the health sector.