Food webs are ecological maps that help ecologists describe and understand complex species interactions. Although most species are parasitic, most food webs don’t have parasites. As a result, classic ecological theory has not considered little role for parasites. Whether this matters depends on the roles that parasites play in terms of their biomass density, their effects on hosts, and how they modify predator-prey interactions. On the other hand, although food webs might affect parasite transmission and responses to ecological change, epidemiologists rarely think about disease transmission in a food-web context. Putting parasites and food webs together is technically challenging, but it can give new insights to ecology and disease transmission.