Ethylene Oxide (EtO) sterilizers are a crucial method for sterilizing heat- and moisture-sensitive medical devices and materials that cannot be sterilized by steam or hydrogen peroxide. EtO is a gas that penetrates packaging and porous materials, alkylating proteins and nucleic acids of microorganisms, thereby killing bacteria, viruses, fungi, and spores. The process occurs at lower temperatures (typically 30-60°C) over several hours, followed by a lengthy aeration phase to remove residual EtO, which is toxic and carcinogenic. EtO sterilization is used for complex medical devices containing electronics, plastics, or multiple lumens, such as pacemakers, catheters, and certain endoscopes. While effective, its use requires stringent safety protocols due to its hazardous nature, making it a specialized sterilization method primarily performed in large central sterile processing departments or by contract sterilizers.