In 1922 Dr H.A. Baylis, then head of what today is the Parasitic worms group, devised a Host-Parasite Catalogue in which he recorded the host-parasite associations published in the scientific literature. The catalogue, which is in manuscript form, was maintained by the group staff until 1988. It contains lists of the helminth parasites recorded under genus of host and is fully cross-referenced with parasite-host and bibliographic files. By 1988 data had been extracted from more than 70,000 references. Between 1988 and 2003 new records were entered into a computerised database which includes additional details on host-species and locality. This database includes more than a quarter of a million host-parasite records extracted from 28,000 references. A partial implementation [lacking details on synonymy, comments (e.g. larva) and subject (keywords)] can be searched on-line at https://www.nhm.ac.uk/research-curation/scientific-resources/taxonomy-systematics/host-parasites/database/index.jsp. This resources in this dataset contain a full export of the data underlying the online catalogue; it is not intended to be a replacement interface and is hosted here purely to faciliate resuse of the dataset in its entirety.