Hydrogen sulfide, a substance found in many workplaces, can be an invisible, silent killer if safe work practices aren't followed. Employees can work safely in areas with the potential of this dangerous gas by following their organization's Hydrogen Sulfide Contingency Plan, knowing how and when to use respiratory protection, and knowing the meaning of their facility's hydrogen sulfide warning sounds and signals. This program reviews these three key issues and many other precautions that protect employees from H2S exposures when followed.