Biological invasions cause billions of dollars in economic damage each year and are a serious threat to native biodiversity. Introduced species often escape most of the parasite and pathogen species from their native range. While they can also bring parasites with them and accumulate novel parasites from their new location, this is generally only a fraction of the number lost. Introduced populations are also generally less frequently infected (prevalence - % individuals infected) compared to native conspecific populations. I discuss patterns of parasite release across a broad range of aquatic and terrestrial species and give some specific examples of how this may influence invasions in marine systems. In conjunction with other biological and physical factors, release from parasites can explain the increased demographic performance of invasive species, thereby accounting for much of the damage they cause.