Hepatitis E is a viral disease that presents as acute hepatitis in humans. The etiological agent is hepatitis E virus (HEV), first identified in the early 1980s. The disease is an important public health issue in developing countries where it is frequently epidemic. Industrialized countries were previously thought to be free from HEV, with a limited number of cases reported only in people who had traveled to endemic areas. However, more recent studies have documented an increasing number of sporadic cases in developed areas, among patients who had no history of travelling to countries endemic for hepatitis E. Furthermore, a high anti-HEV seroprevalence has been detected among healthy individuals in nonendemic countries. Since the early 1990s, serological evidence of HEV infection and virus detection have been reported in many animal species in both developed and developing countries, suggesting that these host species may become infected with HEVlike viruses. In 1997, a swine HEV strain was identified for the first time in the United States. This swine HEV strain correlated genetically to two human HEV strains isolated in the United States during the same period from patients who had not traveled to endemic areas. Since then, swine HEV strains have been isolated across the globe. A strict genetic correlation between human and swine strains from the same geographic region has been observed frequently, and cross-species transmission of swine strains to humans and of human strains to nonhuman primates has been demonstrated. Furthermore, several seroepidemiological studies have reported high antibody prevalence to HEV in people working in direct contact with swine or wild boar.The first direct evidence of a possible zoonotic transmission of HEV was provided in Japan in 2003, when cases of hepatitis E were associated to the ingestion of uncooked meat or organs from pigs, wild boar, or deer. More recently, a study conducted in France confirmed that 13 human cases of hepatitis E were eventually linked to the consumption of raw figatellu pig liver sausages. The disease is now recognized as an emerging zoonosis.