Health care workers are exposed to blood-borne pathogens, mainly the human immunodeficiency virus, hepatitis B virus and hepatitis C virus. Infection by these viruses leads to chronic or fatal illnesses which are expensive and difficult to treat. Individuals who harbour these viruses may be asymptomatic and hence all patients should be assumed to harbour a blood-borne pathogen. All health care workers should take adequate precautions (a set of guidelines termed 'universal precautions'). Methods of preventing transmission of blood-borne pathogens include vaccination against hepatitis B virus, following universal precautions and taking adequate post-exposure prophylaxis.