Abstract: Seabirds are well known to be hosts of a diverse set of parasites and pathogens. Most seabird species are also widely distributed, migratory, long-lived, colonial and site faithful. Such characteristics mean seabirds are potentially important model systems for investigating host-parasite interactions at a hierarchy of temporal and spatial scales. Key issues regarding the ecology and evolution of these interactions notably concern factors affecting dispersal of hosts and parasites among colony patches, but also local interactions between individual hosts and parasites, which can involve the transgenerational transfer of immunity through the egg. Using studies conducted with kittiwakes and the tick Ixodes uriae, but also other seabird species, notably the Indian yellow-nosed albatross and sub-Antarctic skua, I will illustrate how important of basic and applied questions can be addressed using such systems, with implication from comparative immunology to conservation.