A parasite is defined as any organism living within or on another living creature and deriving advantage from doing so while causing disadvantage to the host. Parasites may spend part or all of their life cycle with the host. The epidemiology and transmission of most parasites is well defined. Parasites are rarely spread by direct person-to-person contact; therefore, they usually require little attention from infection preventionists. However, infestations with ectoparasites or epidermal parasites are fairly common among the community and healthcare facilities and can be responsible for infections of the epidermis or external layer of the skin. Healthcare-associated transmission has been reported with scabies, lice, and maggots. This chapter focuses on parasites (primarily ectoparasites) that may directly affect the healthcare setting but also briefly covers those that may be seen in individual patients.