Hepatitis E virus (HEV) causes self-limiting acute icteric hepatitis and has epidemiological and clinical characteristics similar to those of hepatitis A virus (HAV) infection. The virus has been responsible for major outbreaks of infection in many developing countries in Asia, Africa and Latin America, whilst in industrialised countries of the West it is acquired through zoonotic transmission from animal reservoirs. The infection is particularly serious during pregnancy, whilst progressive liver disease has been described in immunosuppressed individuals who have been transplanted or are HIV positive.