This investigation is a preliminary examination of sexual orientation as a social vulnerability for experiencing HIV-/AIDS-related stigma, specifically concerns about disclosure and public attitudes. Participants were 36 heterosexual men and 82 gay men with HIV/AIDS. Consistent with predictions, a heterosexual sexual orientation was significantly associated with HIV/AIDS disclosure concerns. This effect was evident after controlling for various demographic variables, CD4 T-cell count, time since HIV diagnosis, self-esteem, and coping styles. Also as predicted, similar levels of enacted stigma were evident, regardless of sexual orientation. Further work is needed to understand the process of HIV/AIDS disclosure for heterosexual men with this illness and to differentiate the experience of HIV-/AIDS-related stigma among gay and straight men with HIV/AIDS.