At least 14 studies since the late 1980's converge into a consistent pattern: compared to other IDUs, WSW IDUs report higher levels of HIV-related risk behaviors and in many cases exhibit higher rates of HIV seroconversion or seroprevalence. Data from these and additional studies also indicate that large numbers of women IDUs are WSWs. Because information regarding WSW IDUs is widely collected but infrequently analyzed and reported, this article suggests promising research and analysis strategies by exploring the meaning behind this pattern of increased vulnerability to HIV. The article asserts that enough is currently known to warrant significant investment in targeted prevention and intervention programs to address the critical HIV-related needs of lesbian, bisexual, and other WSW IDUs. It emphasizes the need for ethnographic and other qualitative research in the area. Tables, notes, references