In the United States, a major federally-funded approach to HIV-1 prevention for injecting drug users (IDUs) includes teaching them to always rinse their needles/syringes with household bleach and water before use. This report describes interdisciplinary studies of the extent to which HIV-1 can be found in injection equipment and the efficacy of bleach as a disinfectant, under simulated field conditions. Bloody needle/syringe units collected from Miami, Florida, shooting galleries or from community outreach prevention participants were selected for these studies. Groups of needle/syringe units were cleansed with bleach using a standard technique taught to IDUs in community outreach programs. Cleansed and uncleansed groups of needles/syringe units were then tested for the presence of HIV-1. The data demonstrate the efficacy of bleach rinses in reducing the risks of HIV-1 infection from needle/syringe units and indicate that the teaching of a bleach cleansing method to IDUs should be part of a total AIDS prevention protocol.