Hepatitis resulting from viral infection is common worldwide and is associated with significant morbidity and mortality. Caused by a group of unrelated viruses that target the liver, hepatitis E virus is not well understood and is consequently often perceived in many countries as unimportant. This article describes the main features of hepatitis E virus and reviews global patterns of transmission, endemicity and the variable clinical outcomes of infection, especially in pregnant women and anyone who is immunocompromised. Infection prevention measures are also discussed.