Hepatitis E represents a significant proportion of enteric transmitted liver diseases and poses a major public health problem, mainly associated with epidemics due to contamination of water supplies, especially in developing countries. Hepatitis E virus (HEV) is responsible for self-limiting acute liver oral-faecal infections. In industrialised countries, acute hepatitis E is sporadic, detected in travellers from endemic areas but also in sporadic cases with no risk factors. HEV is a non-enveloped virus with a single-stranded RNA genome classified into 4 genotypes and a single serotype. Genotypes 1 and 2 only infect humans, and are predominant in the developing countries, while 3 and 4 are predominant in industrialised countries, and also infect other species of mammals, especially pigs, and multiple evidence classifies HEV as a zoonotic agent. Some HEV chronic infections have recently been reported in kidney and liver transplant patients. The mortality rate of HEV infection is greater than hepatitis A. In addition to faecal-oral transmission, parenteral transmission of HEV has also been reported. Several vaccines are currently in development. The severity of this infection in some groups of patients, especially pregnant women, and the occurrence of chronic hepatitis, even with progression to cirrhosis, have raised interest in the application of interferon and/or ribavirin therapy.