This study sought to identify predictors of HIV disclosure and serodiscordant unprotected anal intercourse (SDUAI) among HIV-positive men who have sex with men (MSM). Between January 2005 and April 2006, 675 HIV-positive MSM were recruited into the Positive Connections intervention trial held in six US cities with intentional over-sampling of HIV-positive MSM of Color (74%) and men engaging in unprotected anal intercourse (UAI) in the previous year. Baseline survey data showed 30 and 31%, respectively, of participants disclosed to none or some of their secondary sex partners in the last 90 days. Greater disclosure to secondary partners was associated with having fewer sexual partners, being extremely out as MSM, longer HIV diagnosis, knowledge of CD4 count, detectable viral load and being white. Disclosure to all secondary partners was associated with lower SDUAI. Recommendations for prevention for HIV-positive MSM include the promotion of serodisclosure to all secondary partners and increasing comfort with, and outness about, one's sexuality.