At the heart of the recommendations to prevent HIV transmission in workers who perform high-risk tasks are the universal blood and body fluid precautions. These precautions are meant to be followed by all health-care workers in the care of all patients and by public safety workers (e.g., firefighters, police officers, and correctional facility personnel) whenever they perform specific tasks that expose them to blood, body fluids, or tissues. Universal precautions apply to blood, semen, vaginal secretions, body tissues, cerebrospinal fluid, synovial fluid, pleural fluids, peritoneal fluid, pericardial fluid, and amniotic fluid. These fluids have either been implicated in HIV transmission or their risk of transmission is unknown. Other fluids or excretions are excluded from universal precautions because epidemiologic studies have failed to implicate them in HIV transmission. These include feces, nasal secretions, sputum, sweat, tears, urine, vomitus, breast milk, and saliva, unless they contain visible blood. However, routine precautions (handwashing, gloves, etc.) to prevent exposure to other diseases transmitted by these media should be followed. Other precautions are directed at health-care workers who perform specialized at-risk procedures, e.g., surgeons, dentists, laboratory workers, etc. In general, recommendations for these workers include the universal precautions plus additional emphasis on the use of barrier measures. Although the risk of environmentally mediated HIV transmission is negligible, it is theoretically possible, and recommendations to kill or inactivate HIV on environmental surfaces should be followed. Fortunately, HIV is easily inactivated in the environment. The cheapest and most convenient method is a 1:10 or 1:100 dilution of household bleach.(ABSTRACT TRUNCATED AT 250 WORDS)