Summary. Although autochthonous hepatitis E has been reported in developed countries, its extent and nature in the United Kingdom are unclear. The aim of the present study was to report the natural history, lifestyle risk factors and molecular epidemiology of autochthonous hepatitis E infection in southwest England. Three hundred and thirty-three patients with unexplained hepatitis were tested for markers of hepatitis E virus (HEV) infection over a 7-year period. HEV RNA isolated from the cases was amplified and characterized. Of the 333 patients, 21 had autochthonous hepatitis E. Patients were middle-aged or elderly and males were more commonly affected. Clinical manifestations ranged from asymptomatic infection to severe hepatitis. Of the 21 patients, 20 recovered within 6 weeks. None of the cases had travelled to an area endemic for HEV. None of the patients were vegetarian and all ate pork. Of the 21 cases, 20 occurred in the spring, summer and autumn months. All polymerase-chain-reaction-confirmed cases carried HEV genotype 3, which bore close sequence homology to HEV circulating in UK pigs. In the United Kingdom, autochthonous hepatitis E may be more common than previously recognized. Although the mode of transmission remains to be determined, it may be a zoonosis with pigs as a reservoir. Hepatitis E should be considered a public health issue in the United Kingdom.