The HIV epidemic has disproportionately affected marginalized populations. Societal marginalization contributes to the lack of appropriate prevention programs focusing on these populations, which in turn may contribute to ongoing HIV transmission. Transmen (female-to-male transgender persons) may also be a marginalized population at risk for HIV infection. Unfortunately, few studies that focus on transmen have been conducted. We considered the available existing data sources that may include members of the transmen population in San Francisco to describe what is known and what remains to be understood with respect to their risk for HIV. Data used for this descriptive analysis were collected at HIV test sites in 2009. In 2009, 59 unduplicated test seekers identified as transmen. While behavioral risk factors present in this study point to the high potential for HIV risk, there may still be low HIV prevalence and time to intervene. Lest we be caught off guard as another marginalized sexual minority experiences the tragedy of a rapid HIV epidemic, more detailed, specifically designed studies are needed to complete what we do not know about this population.