The hepatitis E virus (HEV), the causative agent of hepatitis E, is a non-enveloped RNA virus. The HEV genome is formed by a non-segmented positive-sense RNA chain. The 3'end of the chain is polyadenylated and the 5'end is structurally characterised by the so called capping. According to currently accepted taxonomy, HEV is classified in the genus Hepevirus, the only member of the Hepeviridae family. HEV is usually transmitted via the faecal-oral route due to the fact that drinking water or water for industrial purposes is contaminated due to poor sanitation. This spread of HEV was reported in developing countries of Asia, Africa, South and Central America. However, cases in countries with the sporadic occurrence of HEV were associated with travelling to countries with an increased risk of infection. HEV infections were subsequently described in people who did not travel to endemic countries. Further studies of the HEV suggested other routes of transmission and a zoonotic potential of the virus (pigs and deer as the potential source of human infection).