The widespread screening of donors of blood, organs and semen for HIV antibody has contributed greatly to the prevention of spread of HIV to patients in British hospitals. The chances of patients acquiring HIV from a contaminated blood transfusion are now estimated at less than 1 in 1 million and factor VIII for haemophiliacs, which is also heat treated, is now virtually always free of HIV contamination. However, the wider use of HIV antibody tests to identify infected patients and rationalize the application of additional 'inoculation risk' precautions, so as to protect staff, is controversial. The risks of hospital staff acquiring HIV following occupational exposure, without such a screening-programme, are extremely low provided a high standard of hygiene is maintained and inoculation injuries are avoided. When needlestick injuries occur, involving HIV infected patients, the chances of transmission of HIV to hospital staff are less than 1 in 100. Current guidelines in Britain depend on use of additional inoculation precautions for patients belonging to HIV risk groups but in practice most of these 'risk patients' are not infected with HIV. Screening HIV antibody tests, preferably with consent, can help the smooth running of operating theatres in areas where many 'risk patients' require surgery, as extra precautions are not necessary for most of these patients who are HIV negative. All antenatal patients should be screened especially in areas of high prevalence of HIV, as this helps to prevent vertical transmission as well as facilitating the rational use of extra precautions to protect health care workers.