Since 1986, scrapie-like spongiform encephalopathy has been diagnosed in 19 captive wild animals of eight species at or from eight zoological collections in the British Isles. The affected animals have comprised members of the family Bovidae: one nyala (Tragelaphus angasi), four eland (Taurotragus oryx), and six greater kudu (Tragelaphus strepsiceros), one gemsbok (Oryx gazella), one Arabian oryx (Oryx leucoryx), and one scimitar-horned oryx (Oryx dammah), and members of the family Felidae: four cheetah (Acinonyx jubatus) and one puma (Felis concolor). In addition, three cases of a spongiform encephalopathy of unknown aetiology have been reported in ostriches (Struthio camellus) from two zoos in north west Germany. Three features suggest that some of these cases may have been caused by the agent of bovine spongiform encephalopathy (BSE). First, they have been temporally and geographically coincident with the BSE epidemic. Secondly, in all the ungulates for which details are available, it is possible that either the affected animal itself, or the herd into which it was born or moved, had been exposed to proprietary feeds containing ruminant-derived protein or other potentially contaminated material, and all the carnivores had been fed parts of cattle carcases judged unfit for human consumption. Thirdly, the pathological results of inoculating mice with a homogenate of fixed brain tissue from the nyala and from one greater kudu were similar to the results of inoculating mice with BSE brain tissue.