Health care workers, especially surgeons, are frequently exposed to blood. Most blood exposures are not reported. Blood exposures involve risk of contracting serious infectious diseases like HIV, hepatitis B and hepatitis C. Fifty-four cases of occupational transmission of HIV-virus have been reported world wide. Occupational HIV-infection has not been reported in Denmark. Hepatitis B infection can be prevented by vaccination, but there is no effective drug or vaccine to prevent infection with hepatitis C and HIV-virus. Thus, the prevention of occupationally transmitted infections should concentrate on the prevention of blood exposures. Further studies on occupational blood exposure among Danish health care workers are needed.