In the germ-free laboratory, personal protective equipment (PPE) is used either for protection of animals and materials from contamination or for protection of the user from contact with toxins or pathogens. We use three levels of PPE. PPE used for protection of animals in isolators is fairly minimal because the isolator itself prevents contact with microorganisms. For this reason, normal operation requires only latex gloves, plastic gown, and possibly face mask or hair bonnet for preventing contamination of the outside of the isolator in case the isolator itself is damaged (all-purpose PPE). Handling of germ-free animals in class II biosafety cabinets requires a surgical level of sterility to prevent any contact between the user and the cage, animals, surfaces, or anything else (sterile PPE). Finally, respirator PPE, used to protect the user from toxins or infectious agents, consists of full-body protection (gloves, gown, hair bonnet) and a respirator.